'installutil' is not recognized as an internal or external command, operable program or batch file.

You get this error when you type 'installutil.exe' in a command prompt.

Reason: .net folder path is not set in the 'PATH' variable because of which location of installutil.exe was not found.

Resolution:

a) Use the visual studio command prompt, it will work there
b) Set .NET folder path in system's 'PATH' variable . Then try it should get the path of 'installutil.exe' and you can use it directly in any command prompt.

c) Use Coding

It's is really easy to just add it to the service itself. Add a reference to System.Configuration.Install and then update your Main()-function in Program.cs like this.

static void Main(string[] args)
{
    if (Environment.UserInteractive)
    {
        string parameter = string.Concat(args);
        switch (parameter)
        {
            case "--install":
            ManagedInstallerClass.InstallHelper(new[] { Assembly.GetExecutingAssembly().Location });
            break;
            case "--uninstall":
            ManagedInstallerClass.InstallHelper(new[] { "/u", Assembly.GetExecutingAssembly().Location });
            break;
        }
    }
    else
    {
        ServiceBase[] servicesToRun = new ServiceBase[] 
                          { 
                              new ValidatorService() 
                          };
        ServiceBase.Run(servicesToRun

Then you can just call WindowsService1.exe with the --install argument and it will install the service and you can forget about InstallUtil.exe.