static void Main(string[] args) { WcfServiceClient client = new WcfServiceClient(); client.ClientCredentials.UserName.UserName = "******"; client.ClientCredentials.UserName.Password = "******"; client.ClientCredentials.ServiceCertificate.Authentication.CertificateValidationMode = X509CertificateValidationMode.None; // Add the below only in DEV machines. // **** DO NOT ADD THIS IN PRODUCTION **** System.Net.ServicePointManager.ServerCertificateValidationCallback += delegate(object sender, X509Certificate certificate, X509Chain chain, SslPolicyErrors errors) { return(true); }; var response = client.GetRamdomGuid(); Console.WriteLine(response); }