diff --git a/PiwigoDotnet/Piwigo.Client.Tests/ImageApiTests.cs b/PiwigoDotnet/Piwigo.Client.Tests/ImageApiTests.cs
index 68d8656..135a09f 100644
--- a/PiwigoDotnet/Piwigo.Client.Tests/ImageApiTests.cs
+++ b/PiwigoDotnet/Piwigo.Client.Tests/ImageApiTests.cs
@@ -1,3 +1,4 @@
+using System.Text;
 using Microsoft.Extensions.Logging.Abstractions;
 using Piwigo.Client.Contract;
 
@@ -14,6 +15,24 @@ public class ImageApiTests : ApiTestsBase
         _imageApi = new ImageApi(Context, new NullLogger<ImageApi>());
     }
 
+    [Test]
+    public async Task AddChunk_should_post_base64_encoded_data()
+    {
+        SetOkResult();
+
+        var bytes = Encoding.UTF8.GetBytes("PiwigoTestString");
+        var expectedBase64 = Convert.ToBase64String(bytes);
+
+        await _imageApi.AddChunkAsync(bytes, "origSum", 0);
+
+        CorrectMethodShouldGetCalled("pwg.images.addChunk");
+
+        CorrectParamShouldGetSent("data", expectedBase64);
+        CorrectParamShouldGetSent("original_sum", "origSum");
+        CorrectParamShouldGetSent("type", "file");
+        CorrectParamShouldGetSent("position", "0");
+    }
+
     [Test]
     public async Task GetImages_should_return_expected_images()
     {
diff --git a/PiwigoDotnet/Piwigo.Client/IImageApi.cs b/PiwigoDotnet/Piwigo.Client/IImageApi.cs
index 60236aa..b1bdb4e 100644
--- a/PiwigoDotnet/Piwigo.Client/IImageApi.cs
+++ b/PiwigoDotnet/Piwigo.Client/IImageApi.cs
@@ -4,6 +4,8 @@ namespace Piwigo.Client;
 
 public interface IImageApi
 {
+    Task AddChunkAsync(byte[] data, string originalSum, int position, CancellationToken cancellationToken = default);
+
     Task<PagedImages> GetImages(int albumId, bool recursive, PagingInfo page, ImageFilter filter, ImageOrder order = ImageOrder.Name,
         CancellationToken cancellationToken = default);
 }
\ No newline at end of file
diff --git a/PiwigoDotnet/Piwigo.Client/ImageApi.cs b/PiwigoDotnet/Piwigo.Client/ImageApi.cs
index 0299592..2f026db 100644
--- a/PiwigoDotnet/Piwigo.Client/ImageApi.cs
+++ b/PiwigoDotnet/Piwigo.Client/ImageApi.cs
@@ -15,6 +15,22 @@ public class ImageApi : IImageApi
         _logger = logger ?? throw new ArgumentNullException(nameof(logger));
     }
 
+    public async Task AddChunkAsync(byte[] data, string originalSum, int position, CancellationToken cancellationToken = default)
+    {
+        var base64Data = Convert.ToBase64String(data);
+
+        var formParams = new Dictionary<string, string>
+        {
+            { "data", base64Data },
+            { "original_sum", originalSum },
+            // type = file is required for compatibility reasons.
+            // There is no other value allowed
+            { "type", "file" },
+            { "position", position.ToString() }
+        };
+        await _context.PostAsync<PiwigoResponse>(_logger, "pwg.images.addChunk", formParams, cancellationToken);
+    }
+
     public async Task<PagedImages> GetImages(int albumId, bool recursive, PagingInfo page, ImageFilter filter, ImageOrder order = ImageOrder.Name,
         CancellationToken cancellationToken = default)
     {