Speaking to The Xtra Factor presenters Caroline Flack and Olly Murs on the show last night (December 1), Barlow said that he critiques Maloney every week.
Barlow said: "Chris gets lots of criticism from me. I'm on his case all the time about his timing and the way he sings his phrases."
The 41-year-old singer also said he was "really critical" of the Liverpudlian, but did admit that Maloney "comes out every week and sings well".
Maloney sang two songs on The X Factor last night. His first performance, a cover of 'You Raise Me Up', won praise from all four judges.
However his second - a rendition of 'I Just Haven't Met You Yet' - made for mixed reviews from the panel.
Photo gallery - The X Factor semi-final: