diff --git a/crates/ruma-client-api/src/uiaa.rs b/crates/ruma-client-api/src/uiaa.rs
index 603d6080b9..0e8be6fefe 100644
--- a/crates/ruma-client-api/src/uiaa.rs
+++ b/crates/ruma-client-api/src/uiaa.rs
@@ -61,6 +61,12 @@ pub enum AuthData {
     /// This type is only valid during account registration.
     Terms(Terms),
 
+    /// OAuth 2.0 (`m.oauth`).
+    ///
+    /// This type is only valid with the cross-signing keys upload endpoint, after logging in with
+    /// the OAuth 2.0 API.
+    OAuth(OAuth),
+
     #[doc(hidden)]
     _Custom(CustomAuthData),
 }
@@ -100,6 +106,9 @@ impl AuthData {
             "m.registration_token" => Self::RegistrationToken(deserialize_variant(session, data)?),
             "org.matrix.login.jwt" => Self::Jwt(deserialize_variant(session, data)?),
             "m.login.terms" => Self::Terms(deserialize_variant(session, data)?),
+            "m.oauth" | "org.matrix.cross_signing_reset" => {
+                Self::OAuth(deserialize_variant(session, data)?)
+            }
             _ => {
                 Self::_Custom(CustomAuthData { auth_type: auth_type.into(), session, extra: data })
             }
@@ -123,6 +132,7 @@ impl AuthData {
             Self::FallbackAcknowledgement(_) => None,
             Self::Jwt(_) => Some(AuthType::Jwt),
             Self::Terms(_) => Some(AuthType::Terms),
+            Self::OAuth(_) => Some(AuthType::OAuth),
             Self::_Custom(c) => Some(AuthType::_Custom(PrivOwnedStr(c.auth_type.as_str().into()))),
         }
     }
@@ -139,6 +149,7 @@ impl AuthData {
             Self::FallbackAcknowledgement(x) => Some(&x.session),
             Self::Jwt(x) => x.session.as_deref(),
             Self::Terms(x) => x.session.as_deref(),
+            Self::OAuth(x) => x.session.as_deref(),
             Self::_Custom(x) => x.session.as_deref(),
         }
     }
@@ -180,8 +191,8 @@ impl AuthData {
                 Cow::Owned(serialize(RegistrationToken { token: x.token.clone(), session: None }))
             }
             Self::Jwt(x) => Cow::Owned(serialize(Jwt { token: x.token.clone(), session: None })),
-            // Dummy, fallback acknowledgement, and terms of service have no associated data
-            Self::Dummy(_) | Self::FallbackAcknowledgement(_) | Self::Terms(_) => {
+            // Dummy, fallback acknowledgement, terms of service, and OAuth have no associated data
+            Self::Dummy(_) | Self::FallbackAcknowledgement(_) | Self::Terms(_) | Self::OAuth(_) => {
                 Cow::Owned(JsonObject::default())
             }
             Self::_Custom(c) => Cow::Borrowed(&c.extra),
@@ -202,6 +213,7 @@ impl fmt::Debug for AuthData {
             Self::Jwt(inner) => inner.fmt(f),
             Self::FallbackAcknowledgement(inner) => inner.fmt(f),
             Self::Terms(inner) => inner.fmt(f),
+            Self::OAuth(inner) => inner.fmt(f),
             Self::_Custom(inner) => inner.fmt(f),
         }
     }
@@ -235,6 +247,9 @@ impl<'de> Deserialize<'de> for AuthData {
             }
             Some("org.matrix.login.jwt") => from_raw_json_value(&json).map(Self::Jwt),
             Some("m.login.terms") => from_raw_json_value(&json).map(Self::Terms),
+            Some("m.oauth" | "org.matrix.cross_signing_reset") => {
+                from_raw_json_value(&json).map(Self::OAuth)
+            }
             None => from_raw_json_value(&json).map(Self::FallbackAcknowledgement),
             Some(_) => from_raw_json_value(&json).map(Self::_Custom),
         }
@@ -284,6 +299,13 @@ pub enum AuthType {
     #[ruma_enum(rename = "m.login.terms")]
     Terms,
 
+    /// OAuth 2.0 (`m.oauth`).
+    ///
+    /// This type is only valid with the cross-signing keys upload endpoint, after logging in with
+    /// the OAuth 2.0 API.
+    #[ruma_enum(rename = "m.oauth", alias = "org.matrix.cross_signing_reset")]
+    OAuth,
+
     #[doc(hidden)]
     _Custom(PrivOwnedStr),
 }
@@ -506,6 +528,24 @@ impl Terms {
     }
 }
 
+/// Data for an [OAuth 2.0-based] UIAA flow.
+///
+/// [OAuth 2.0-based]: https://spec.matrix.org/latest/client-server-api/#oauth-authentication
+#[derive(Clone, Debug, Default, Deserialize, Serialize)]
+#[cfg_attr(not(ruma_unstable_exhaustive_types), non_exhaustive)]
+#[serde(tag = "type", rename = "m.oauth")]
+pub struct OAuth {
+    /// The value of the session key given by the homeserver, if any.
+    pub session: Option<String>,
+}
+
+impl OAuth {
+    /// Construct an empty `OAuth`.
+    pub fn new() -> Self {
+        Self::default()
+    }
+}
+
 #[doc(hidden)]
 #[derive(Clone, Deserialize, Serialize)]
 #[non_exhaustive]
@@ -708,6 +748,26 @@ impl AuthFlow {
     }
 }
 
+/// Parameters for an [OAuth 2.0-based] UIAA flow.
+///
+/// [OAuth 2.0-based]: https://spec.matrix.org/latest/client-server-api/#oauth-authentication
+#[derive(Clone, Debug, Deserialize, Serialize)]
+#[cfg_attr(not(ruma_unstable_exhaustive_types), non_exhaustive)]
+pub struct OAuthParams {
+    /// A URL pointing to the homeserver's OAuth 2.0 account management web UI where the user can
+    /// approve the action.
+    ///
+    /// Must be a valid URI with scheme `http://` or `https://`, the latter being recommended.
+    pub url: String,
+}
+
+impl OAuthParams {
+    /// Construct an `OAuthParams` with the given URL.
+    pub fn new(url: String) -> Self {
+        Self { url }
+    }
+}
+
 /// Contains either a User-Interactive Authentication API response body or a Matrix error.
 #[derive(Clone, Debug)]
 #[allow(clippy::exhaustive_enums)]