The Manchester City keeper has been dropped by manager Manuel Pellegrini following a string of error-strewn performances, but Szczesny feels that Hart's class is permanent.
"I personally rate him as one of the best, if not the best, goalkeeper in the world," Szczesny told The Mirror.
"You look at Petr Cech (at Chelsea) and he has been amazingly consistent over the last four or five years, but at 25-years-old, you don't have that. So it makes it more exciting.
"Over the last couple of years he was the most consistent and one of the best – it is hard to say the best – goalkeepers in the world and I am sure that he will prove that to people even though he has had some difficult times."
Hart has not played for City since his last-minute mistake led to Fernando Torres scoring the winning goal in the 2-1 defeat to Chelsea on October 27.