Mahon captained Watford to promotion to the Premier League in 2005/06
Crystal Palace have taken Gavin Mahon on loan from Queens Park Rangers until the end of the season.
Mahon, 34, has not featured for the Championship leaders this season but will add some much-needed experience to Palace's fight against relegation.
"I'm very much pleased to have joined. It's been stop-start for me this season and I need to be playing in and amongst the first team," Mahon said.
"If I can give some input off the pitch as well as on it that will be great."
The veteran was released by the club in the summer but rejoined in October on a short-term deal. His last first-team game was on 7 November 2009.