Based on another solutions. I have use this:
IntPtr xAsIntPtr = new IntPtr(excelObj.Application.Hwnd);
excelObj.ActiveWorkbook.Close();
System.Diagnostics.Process[] process = System.Diagnostics.Process.GetProcessesByName("Excel");
foreach (System.Diagnostics.Process p in process)
{
if (p.MainWindowHandle == xAsIntPtr)
{
try
{
p.Kill();
}
catch { }
}
}
Using the "MainWindowHandle" to identify the process and close him.
excelObj: This is my Application Interop excel objecto