Hansard said his first meeting with Morrison was a rather awkward one when he was 19 or 20 at the star's birthday party at a member of the Guinness family's home.
As Morrison jammed in the kitchen, Hansard said his request for one of his songs (Hungry For Your Love) was met with a gruff response from Morrison.
Later, at his friend's urging, Morrison passed his guitar to Hansard to play then promptly walked out of the room.
"I'm thinking 'the only guy I want to actually sing to is gone'," Hansard told Kevin Pollak's Chat Show.
Morrison returned during Hansard's second song and then asked the Dubliner to play the song he had requested earlier, before joining in singing it.
The two then went upstairs and took turns playing their songs to each other.
"I'm getting to sit and observe a master at work up close," Hansard said.
"We passed the guitar back and forth and I ran out of songs after an hour and a half and Van kept going and going."
He said as Morrison was leaving at the end of their jam session he said: "Nice voice, nice songs, blah, blah, blah."