using Spire.Doc;

namespace WordToHTML
{
    class Program
    {
        static void Main(string[] args)
        {
            //Créez une instance de document
            Document mydoc = new Document();

            //Chargez un document Word
            mydoc.LoadFromFile("sample.docx");

            //Enregistrer au format HTML
            mydoc.SaveToFile("WordToHTML.html", FileFormat.Html);
        }
    }
}

Imports Spire.Doc
Namespace WordToHTML
    Class Program
        Shared Sub Main(ByVal args() As String)
            'Créez une instance de document
            Dim document As Document = New Document
            'Chargez un document Word
            document.LoadFromFile("sample.docx")
            'Enregistrer au format HTML
            document.SaveToFile("toHTML.html", FileFormat.Html)

        End Sub
    End Class
End Namespace