diff --git a/src/designer/elsa-workflows-studio/src/modules/credential-manager/models/secrets/oauth2.secret.ts b/src/designer/elsa-workflows-studio/src/modules/credential-manager/models/secrets/oauth2.secret.ts
index f39b4ee40b..c87ee264bd 100644
--- a/src/designer/elsa-workflows-studio/src/modules/credential-manager/models/secrets/oauth2.secret.ts
+++ b/src/designer/elsa-workflows-studio/src/modules/credential-manager/models/secrets/oauth2.secret.ts
@@ -74,17 +74,41 @@ export const OAuth2: Secret = {
       type: 'System.String',
       uiHint: 'single-line',
     },
+    {
+      disableWorkflowProviderSelection: false,
+      isBrowsable: true,
+      isReadOnly: false,
+      label: 'Token endpoint client authentication method',
+      name: 'ClientAuthMethod',
+      order: 4,
+      supportedSyntaxes: ['Literal'],
+      type: 'System.String',
+      uiHint: 'dropdown',
+      options: {
+        isFlagsEnum: false,
+        items: [
+          {
+            text: 'Client secret: Basic',
+            value: 'client_secret_basic',
+          },
+          {
+            text: 'Client secret: Post',
+            value: 'client_secret_post',
+          }
+        ]
+      }
+    },
     {
       disableWorkflowProviderSelection: false,
       isBrowsable: true,
       isReadOnly: false,
       label: 'Scope',
       name: 'Scope',
-      order: 4,
+      order: 5,
       supportedSyntaxes: ['Literal'],
       type: 'System.String',
       uiHint: 'single-line',
-    },
+    }
   ],
   type: 'OAuth2',
 };
diff --git a/src/modules/secrets/Elsa.Secrets.Http/Services/OAuth2TokenService.cs b/src/modules/secrets/Elsa.Secrets.Http/Services/OAuth2TokenService.cs
index 33ae2a8555..b37843cfba 100644
--- a/src/modules/secrets/Elsa.Secrets.Http/Services/OAuth2TokenService.cs
+++ b/src/modules/secrets/Elsa.Secrets.Http/Services/OAuth2TokenService.cs
@@ -43,14 +43,20 @@ public async Task<TokenResponse> GetToken(Secret secret, string? authCode, strin
 	{
 		var clientId = secret.GetProperty("ClientId");
 		var clientSecret = secret.GetProperty("ClientSecret");
+		var clientAuthMethod = secret.GetProperty("ClientAuthMethod") ?? "client_secret_basic";
 		var content = new Dictionary<string, string>
 		{
-			{ "grant_type", secret.GetProperty("GrantType") },
-			{ "client_id", clientId },
-			{ "client_secret", clientSecret },
-			{ "offline_access ", "true" }
+			{ "grant_type", secret.GetProperty("GrantType") }
 		};
 
+		if (clientAuthMethod == "client_secret_post")
+		{
+			content.Add("client_id", clientId);
+			if (!string.IsNullOrEmpty(clientSecret))
+			{
+				content.Add("client_secret", clientSecret);
+			}
+		}
 		if (authCode != null)
 		{
 			content.Add("code", authCode);
@@ -67,6 +73,10 @@ public async Task<TokenResponse> GetToken(Secret secret, string? authCode, strin
 		{
 			var httpClient = _httpClientFactory.CreateClient(nameof(OAuth2TokenService));
 			httpClient.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
+			if (clientAuthMethod == "client_secret_basic")
+			{
+				httpClient.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Basic", GenerateAuthorizationValue(clientId, clientSecret));
+			}
 			
 			var response = await httpClient.PostAsync(secret.GetProperty("AccessTokenUrl"), new FormUrlEncodedContent(content));
 			var json = await response.Content.ReadAsStringAsync();
@@ -92,17 +102,28 @@ public async Task<TokenResponse> GetToken(Secret secret, string? authCode, strin
 
 	public async Task<TokenResponse> GetTokenByRefreshToken(Secret secret, string refreshToken)
 	{
+		var clientId = secret.GetProperty("ClientId");
+		var clientSecret = secret.GetProperty("ClientSecret");
+		var clientAuthMethod = secret.GetProperty("ClientAuthMethod") ?? "client_secret_basic";
 		var content = new Dictionary<string, string>
 		{
 			{ "grant_type", "refresh_token" },
-			{ "client_id", secret.GetProperty("ClientId") },
-			{ "client_secret", secret.GetProperty("ClientSecret") },
 			{ "refresh_token", refreshToken }
 		};
+		
+		if (clientAuthMethod == "client_secret_post")
+		{
+			content.Add("client_id", clientId);
+			content.Add("client_secret", clientSecret);
+		}
 
 		try
 		{
 			var httpClient = _httpClientFactory.CreateClient(nameof(OAuth2TokenService));
+			if (clientAuthMethod == "client_secret_basic")
+			{
+				httpClient.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Basic", GenerateAuthorizationValue(clientId, clientSecret));
+			}
 			var response = await httpClient.PostAsync(secret.GetProperty("AccessTokenUrl"), new FormUrlEncodedContent(content));
 			var json = await response.Content.ReadAsStringAsync();
 			var result = JsonConvert.DeserializeObject<TokenResponse>(json);
@@ -135,4 +156,14 @@ public async Task<TokenResponse> GetTokenByRefreshToken(Secret secret, string re
 			throw;
 		}
 	}
+
+	private static string GenerateAuthorizationValue(string clientId, string clientSecret)
+	{
+		var auth = Uri.EscapeDataString(clientId).Replace("%20", "+");
+		if (!string.IsNullOrEmpty(clientSecret))
+		{
+			auth += $":{Uri.EscapeDataString(clientSecret).Replace("%20", "+")}";
+		}
+		return Base64Encode(auth);
+	}
 }
\ No newline at end of file