Open Office XML

FileInfo file = new FileInfo(@"c:\Test.xlsx");
if (file.Exists)
{
    file.Delete();  // ensures we create a new workbook
    file= new FileInfo(@"c:\Test.xlsx");
}

using (Experior.Core.Data.OfficeOpenXml.Excel excel = new Experior.Core.Data.OfficeOpenXml.Excel(newFile))
{
    Experior.Core.Data.OfficeOpenXml.ExcelWorksheet sheet = excel.Workbook.Worksheets.Add("Date");
    sheet.Cells[1, 1].Value = "Data";
    sheet.Cells[3, 1].Value = "1";
    sheet.Cells[3, 2].Value = "2";
    sheet.Cells[4, 1].Value = "3";
    sheet.Cells[4, 2].Value = "4";

    excel.Save();
}