To add a cookie HttpCookie cookie = new HttpCookie("Chocolate", "Choclate cookies are good"); cookie.Expires = DateTime.Now.AddYears(1); // Expire a year from now Response.Cookies.Add(cookie); If you add a cookie with the same name it replaces the old cookie To add to a cookie cookie.Value += " especially when frozen."; Cookie.Expires = DateTime.Now.AddYears(1); Response.Cookies.Add(cookie); to Kill a cookie HttpCookie cookie = new HttpCookie("Chocolate", string.Empty); cookie.Expires = DataTime.Now.AddYears(-1); // expires a year ago, the browser will delete from the users system Response.Cookies.Add(cookie); To Get a Cookie back... HttpCookie cookie = Reuqest.Cookies.Get("Chocolate"); if (cookie == null) { // Cookie doesn't exist } Else { // Cookie exists } Something to note about cookies is that you can't have a comma in your cookie.. So don't try to store "1,2,3,4" in your cookie. if you want to store something with comma's in it, you should replace them with another character and then use the following code to put back in the comma's.. string myString = cookie.Value.Replace(':',','); This will replace all the :'s in the cookie value with comma's