diff --git a/Activout.RestClient.Test/ErrorResponseTextPlainTest.cs b/Activout.RestClient.Test/ErrorResponseTextPlainTest.cs
new file mode 100644
index 0000000..413bf42
--- /dev/null
+++ b/Activout.RestClient.Test/ErrorResponseTextPlainTest.cs
@@ -0,0 +1,96 @@
+using System.Net;
+using System.Net.Http;
+using System.Threading.Tasks;
+using Microsoft.Extensions.Logging;
+using RichardSzalay.MockHttp;
+using Xunit;
+using Xunit.Abstractions;
+
+namespace Activout.RestClient.Test;
+
+public class ErrorResponseTextPlainTest(ITestOutputHelper outputHelper)
+{
+    private const string BaseUri = "https://example.com/api";
+
+    private readonly IRestClientFactory _restClientFactory = Services.CreateRestClientFactory();
+    private readonly MockHttpMessageHandler _mockHttp = new();
+    private readonly ILoggerFactory _loggerFactory = LoggerFactoryHelpers.CreateLoggerFactory(outputHelper);
+
+    private ITestService CreateTestService()
+    {
+        return _restClientFactory.CreateBuilder()
+            .With(_loggerFactory.CreateLogger<ErrorResponseTextPlainTest>())
+            .With(_mockHttp.ToHttpClient())
+            .BaseUri(BaseUri)
+            .Build<ITestService>();
+    }
+
+    private ITestServiceWithCustomError CreateTestServiceWithCustomError()
+    {
+        return _restClientFactory.CreateBuilder()
+            .With(_loggerFactory.CreateLogger<ErrorResponseTextPlainTest>())
+            .With(_mockHttp.ToHttpClient())
+            .BaseUri(BaseUri)
+            .Build<ITestServiceWithCustomError>();
+    }
+
+    [Fact]
+    public async Task TestErrorResponse_TextPlain_BadRequest()
+    {
+        // arrange
+        _mockHttp
+            .When(HttpMethod.Get, $"{BaseUri}/resource")
+            .Respond(HttpStatusCode.BadRequest, "text/plain", "Invalid request parameter");
+
+        var service = CreateTestService();
+
+        // act
+        var exception = await Assert.ThrowsAsync<RestClientException>(() => service.GetResource());
+
+        // assert
+        Assert.Equal(HttpStatusCode.BadRequest, exception.StatusCode);
+        Assert.NotNull(exception.ErrorResponse);
+        Assert.IsType<string>(exception.ErrorResponse);
+        Assert.Equal("Invalid request parameter", exception.GetErrorResponse<string>());
+        Assert.Equal("Invalid request parameter", exception.Message);
+    }
+
+    [Fact]
+    public async Task TestErrorResponse_TextPlain_BadRequest_CustomErrorMessage()
+    {
+        // arrange
+        _mockHttp
+            .When(HttpMethod.Get, $"{BaseUri}/resource")
+            .Respond(HttpStatusCode.BadRequest, "text/plain", "Invalid request parameter");
+
+        var service = CreateTestServiceWithCustomError();
+
+        // act
+        var exception = await Assert.ThrowsAsync<RestClientException>(() => service.GetResource());
+
+        // assert
+        Assert.Equal(HttpStatusCode.BadRequest, exception.StatusCode);
+        Assert.NotNull(exception.ErrorResponse);
+        Assert.IsType<CustomErrorMessage>(exception.ErrorResponse);
+        var customError = exception.GetErrorResponse<CustomErrorMessage>();
+        Assert.Equal("Invalid request parameter", customError.Message);
+    }
+
+    [Path("resource")]
+    [ErrorResponse(typeof(string))]
+    public interface ITestService
+    {
+        [Get]
+        Task GetResource();
+    }
+
+    [Path("resource")]
+    [ErrorResponse(typeof(CustomErrorMessage))]
+    public interface ITestServiceWithCustomError
+    {
+        [Get]
+        Task GetResource();
+    }
+
+    public record CustomErrorMessage(string Message);
+}
diff --git a/Activout.RestClient.Xml.Test/ErrorResponseXmlTest.cs b/Activout.RestClient.Xml.Test/ErrorResponseXmlTest.cs
new file mode 100644
index 0000000..d16b369
--- /dev/null
+++ b/Activout.RestClient.Xml.Test/ErrorResponseXmlTest.cs
@@ -0,0 +1,73 @@
+using System.Net;
+using System.Xml.Serialization;
+using Microsoft.Extensions.Logging;
+using RichardSzalay.MockHttp;
+using Xunit.Abstractions;
+
+namespace Activout.RestClient.Xml.Test;
+
+public class ErrorResponseXmlTest(ITestOutputHelper outputHelper)
+{
+    private const string BaseUri = "https://example.com/api";
+
+    private readonly IRestClientFactory _restClientFactory = Services.CreateRestClientFactory();
+    private readonly MockHttpMessageHandler _mockHttp = new();
+    private readonly ILoggerFactory _loggerFactory = LoggerFactoryHelpers.CreateLoggerFactory(outputHelper);
+
+    private ITestService CreateTestService()
+    {
+        return _restClientFactory.CreateBuilder()
+            .WithXml()
+            .With(_loggerFactory.CreateLogger<ErrorResponseXmlTest>())
+            .With(_mockHttp.ToHttpClient())
+            .BaseUri(BaseUri)
+            .Build<ITestService>();
+    }
+
+    [Fact]
+    public async Task TestErrorResponse_Xml_BadRequest()
+    {
+        // arrange
+        const string errorXml = """
+            <?xml version="1.0" encoding="UTF-8"?>
+            <error>
+                <code>400</code>
+                <message>Invalid request parameter</message>
+            </error>
+            """;
+        _mockHttp
+            .When(HttpMethod.Get, $"{BaseUri}/resource")
+            .Respond(HttpStatusCode.BadRequest, "text/xml", errorXml);
+
+        var service = CreateTestService();
+
+        // act
+        var exception = await Assert.ThrowsAsync<RestClientException>(() => service.GetResource());
+
+        // assert
+        Assert.Equal(HttpStatusCode.BadRequest, exception.StatusCode);
+        Assert.NotNull(exception.ErrorResponse);
+        Assert.IsType<XmlErrorResponse>(exception.ErrorResponse);
+        var errorResponse = exception.GetErrorResponse<XmlErrorResponse>();
+        Assert.Equal(400, errorResponse.Code);
+        Assert.Equal("Invalid request parameter", errorResponse.Message);
+    }
+
+    [Path("resource")]
+    [ErrorResponse(typeof(XmlErrorResponse))]
+    public interface ITestService
+    {
+        [Get]
+        Task GetResource();
+    }
+
+    [XmlRoot("error")]
+    public class XmlErrorResponse
+    {
+        [XmlElement("code")]
+        public int Code { get; set; }
+
+        [XmlElement("message")]
+        public string Message { get; set; } = "";
+    }
+}