---
title: "Get OxidationStateDoc documents"
method: GET
path: "/materials/oxidation_states/"
tags: ["Materials Oxidation States"]
---

# Get OxidationStateDoc documents

`GET /materials/oxidation_states/`

## Query parameters

- `material_ids` string, nullable — Comma-separated list of material_id values to query on
- `formula` string, nullable — Query by formula including anonymized formula or by including wild cards. A comma delimited string list of anonymous formulas or regular formulas can also be provided.
- `chemsys` string, nullable — A comma delimited string list of chemical systems. Wildcards for unknown elements only supported for single chemsys queries
- `possible_species` string — Comma delimited list of element symbols appended with oxidation states. (e.g. Cr2+,O2-)
- `_page` integer — Page number to request (takes precedent over _limit and _skip).
- `_per_page` integer — Number of entries to show per page (takes precedent over _limit and _skip). Limited to 1000.
- `_skip` integer — Number of entries to skip in the search.
- `_limit` integer — Max number of entries to return in a single query. Limited to 1000.
- `_fields` string — Fields to project from OxidationStateDoc as a list of comma separated strings. Fields include: `builder_meta` `nsites` `elements` `nelements` `composition` `composition_reduced` `formula_pretty` `formula_anonymous` `chemsys` `volume` `density` `density_atomic` `symmetry` `material_id` `deprecated` `deprecation_reasons` `last_updated` `origins` `warnings` `structure` `property_name` `possible_species` `possible_valences` `average_oxidation_states` `method`
- `_all_fields` boolean — Include all fields.
- `license` 'BY-C' | 'BY-NC' | 'All', nullable — Query by license. Can be commercial or non-commercial, or both
- `id_format` string, nullable — Optional. If set to 'legacy', MP identifier fields in the response are returned in the form 'mp-149'. If set to 'alpha', they are returned in the padded AlphaID form 'mp-aaaaaaft'. If omitted (or set to any other value), identifiers are returned in their stored form. This is a purely cosmetic transform; query inputs accept either shape regardless.

## Response `200`

Search for a OxidationStateDoc

- ResponseOxidationStateDoc
  - `data` OxidationStateDoc[], nullable — List of returned data
    - `builder_meta` EmmetMeta — Default emmet metadata.
      - `emmet_version` string, nullable — The version of emmet this document was built with.
      - `pymatgen_version` string, nullable — The version of pymatgen this document was built with.
      - `run_id` string, nullable — The run id associated with this data build.
      - `batch_id` string, nullable — Identifier corresponding to the origin of this document's blessed task.
      - `database_version` string, nullable — The database version for the built data.
      - `build_date` string, date-time, nullable — The build date for this document.
      - `license` 'BY-C' | 'BY-NC', nullable — License for the data entry.
    - `nsites` integer, nullable — Total number of sites in the structure.
    - `elements` string[], nullable — List of elements in the material.
    - `nelements` integer, nullable — Number of elements.
    - `composition` object, nullable — Full composition for the material.
    - `composition_reduced` object, nullable — Simplified representation of the composition.
    - `formula_pretty` string, nullable — Cleaned representation of the formula.
    - `formula_anonymous` string, nullable — Anonymized representation of the formula.
    - `chemsys` string, nullable — Dash-separated string of elements in the material.
    - `volume` number, nullable — Total volume for this structure in ų.
    - `density` number, nullable — Density in g/cm³.
    - `density_atomic` number, nullable — The atomic packing density in ų/atom.
    - `symmetry` SymmetryData — Defines a symmetry data set for materials documents
      - `crystal_system` string, nullable — The crystal system for this lattice.
      - `symbol` string, nullable — The spacegroup symbol for the lattice.
      - `hall` string, nullable — Hall symbol for the lattice
      - `number` integer, nullable — The spacegroup number for the lattice.
      - `point_group` string, nullable — The point group for the lattice.
      - `symprec` number, nullable — The precision provided to spglib to determine the symmetry of this structure.
      - `angle_tolerance` number, nullable — Angle tolerance provided to spglib to determine the symmetry of this structure.
      - `version` string, nullable
    - `material_id` unknown
    - `deprecated` boolean — Whether this property document is deprecated.
    - `deprecation_reasons` string[], nullable — List of deprecation tags detailing why this document isn't valid.
    - `last_updated` string, date-time — Timestamp for the most recent calculation update for this property.
    - `origins` PropertyOrigin[], nullable — Dictionary for tracking the provenance of properties.
      - `name` string, required — The property name
      - `task_id` unknown, required
      - `last_updated` string, date-time — The timestamp when this calculation was last updated
    - `warnings` string[] — Any warnings related to this property.
    - `structure` TypedStructureDict, required — unresolved $ref
    - `property_name` string
    - `possible_species` string[], required — Possible charged species in this material.
    - `possible_valences` number[], required — List of valences for each site in this material.
    - `average_oxidation_states` object, required — Average oxidation states for each unique species.
    - `method` string, nullable — Method used to compute oxidation states.
  - `errors` Error[], nullable — Any errors on processing this query
    - `code` integer, required — The error code
    - `message` string, required — The description of the error
  - `meta` Meta — Meta information for the MAPI Response.
    - `api_version` string — A string containing the version of the Materials API implementation, e.g. v0.9.5
    - `time_stamp` string, date-time — A string containing the date and time at which the query was executed
    - `total_doc` integer, nullable — The total number of documents available for this query
    - `facet` object, nullable — A dictionary containing the facets available for this query

## Other responses

- `422` — Validation Error

## Changes

> 4 revisions in range; 1 could not be searched.

- **2026-07-31** `54f2f79ab4f8` — 1 info
  - the `api_version` response's property default value changed from `0.87.2.dev13+g62063a867` to `0.87.2.dev19+g3f2daf4f8` for the status `200`
- **2026-07-26** `9aac4fdf4081` — 1 info
  - the `api_version` response's property default value changed from `0.87.2.dev4+g6bd8ed856` to `0.87.2.dev13+g62063a867` for the status `200`

[Change history](https://skmtc.dev/materialsproject/apis/materials-project-api/changes/materials/oxidation_states/get.md)

---

[API](https://skmtc.dev/materialsproject/apis/materials-project-api.md) · [All operations](https://skmtc.dev/materialsproject/apis/materials-project-api/llms.txt) · [OpenAPI document](https://skmtc-service-production.skmtc.workers.dev/v1/apis/materialsproject/materials-project-api/revisions/70f72d0670df/schema)