Create StreamWriter with encoding
using System; using System.IO; public class SWBuff { public static void Main(String[] args) { string logFile = "a.log"; string fileName = "a.log"; string textToAdd = "asdf"; FileStream fs = new FileStream(fileName, FileMode.CreateNew, FileAccess.Write, FileShare.None); StreamWriter swFromFileStreamDefaultEnc = new System.IO.StreamWriter(fs, System.Text.Encoding.Default); swFromFileStreamDefaultEnc.Write(textToAdd); swFromFileStreamDefaultEnc.Flush(); swFromFileStreamDefaultEnc.Close(); } }