The former Germany international was quick to praise the 28-year-old for the way he has responded after being sidelined last season.
The HSV No.1 has had six cleansheets this campaign, while also received a call-up to the Germany squad in November and Kahn lauded the keeper for his comeback.
Kahn told Bild: “I admire Rene. The fact he has returned stronger is sensational. You have to be mentally strong to work your way back to the top.
“I have seen many footballers who have lost confidence in this situation and have not come back."
Adler was happy to receive such high praise from Kahn, who won 86 caps for his country and won the Champions League with Bayern Munich in 2001.
He said: "It was a nice compliment. Just because it comes from Oliver Kahn, whose commitment and willpower were always commendable indeed."
The HSV shot-stopper has won 10 caps for his country and was set to be Germany’s No.1 at the 2010 World Cup before an injury ruled him out.