static void Main(string[] args) { List <Product> products = new List <Product>(3); products.Add(new Product() { Code = "P_A", Discount = 0.1F, Id = 1, Name = "F-15", Price = 6000.85m, AvailableDate = DateTime.Now }); products.Add(new Product() { Code = "P_B", Discount = 0.2F, Id = 2, Name = "F-16", Price = 5500.50m, AvailableDate = DateTime.Now.AddDays(-3), IsOffline = true, NullableBool = true }); products.Add(new Product() { Code = "P_C", Discount = 0.22F, Id = 3, Name = "F-22", Price = null, AvailableDate = DateTime.Now.AddDays(-3), IsOffline = true, NullableBool = true }); products.Add(new Product() { Code = "P_D", Discount = 0.35F, Id = 4, Name = "F-18", Price = 5800.0m, AvailableDate = DateTime.Now.AddDays(-5) }); string fileName = Path.Combine(Environment.CurrentDirectory, "Test.xlsx"); // create .xlsx file as MemoryStream using (MemoryStream ms = ExcelGenerator.CreateStream(products, "Products")) { using (FileStream fs = File.Create(fileName)) { ms.WriteTo(fs); } } // create .xlsx file //ExcelGenerator.CreateFile(products, "Products", fileName); }