Find out if file is older than 4 hours in Batch file

Alternatively you could create a simple program using C# for example like that:

// compile using c:\Windows\Microsoft.NET\Framework\v3.5\csc FileByAge.cs
using System;
using System.IO;

public static class Program
{
  public static void Main(string[] args)
  {
    double age = double.Parse(args[0]);
    string fileName;
    while ((fileName = Console.ReadLine()) != null)
    {
      if(age >= (DateTime.Now - new FileInfo(fileName).CreationTime).TotalHours)
      {
        continue;
      }
      Console.WriteLine(fileName);    
    }
  }
}

That program could then be used to find all files that are older than 2 hours within a batch file like that:

for /F "delims=" %f in ('dir /B *.txt^|FileByAge.exe 2') do echo %f

An improved and self-compiling version

As mentioned by @Paul one could even build a hacky hybrid batch / c# file that will compile and run itself:

@echo off
setlocal
set CsFile=%TEMP%\%~n0.cs
set ExeFile=%TEMP%\%~n0.exe
pushd %SystemRoot%\Microsoft.NET\Framework
for /F %%f in ('dir /B /O:-N v*') do cd %%f & goto :BreakLoop;  
:BreakLoop
(echo /* & type "%~f0") > "%CsFile%"
csc.exe /nologo /out:"%ExeFile%" "%CsFile%" 
del "%CsFile%"
popd
more | "%ExeFile%" %*
del "%ExeFile%"
endlocal
goto:eof
*/

using System;
using System.IO;

public static class Program
{
    public static void Main(string[] args)
    {
        var olderThen = args[0].Contains("older");
        var targetAge = double.Parse(args[1]);
        string fileName;
        while ((fileName = Console.ReadLine()) != null)
        {
            if (string.Empty == fileName)
            {
                continue;
            }
            var fileAge = (DateTime.Now - new FileInfo(fileName).CreationTime).TotalHours;
            if (olderThen ? targetAge > fileAge : targetAge < fileAge)
            {
                continue;
            }
            Console.WriteLine(fileName);
        }
    }
}

And can be used like this:

for /F "delims=" %f in ('dir /B *.txt^|FileByAge.bat older 2') do echo %f