The 28-year-old central midfielder has been a free agent since leaving Fenerbahce last year having endured a lengthy spell on the sidelines with a serious knee injury.
Appiah spent time on trial at Spurs last January, with both Arsenal and West Ham also linked with moves for the player.
However, nothing ever materialised, with question marks over Appiah's fitness believed to be preventing a deal from being completed.
After training with Russian champions Rubin Kazan, the former Juventus powerhouse then discovered that he could not join a new club until he paid Fenerbahce $2.3 million, after FIFA found in the Turks' favour following a complaint that Appiah breached his contract.
The Black Stars' skipper - who has 53 caps for his country - has most recently been training with former club Brescia's youth team in a bid to improve his fitness.
And although Catania general manager Lo Monaco revealed that he would be interested in acquiring the Ghanaian's services, Schalke boss Felix Magath is now considering making a move for him to add strength and depth to his midfield, according to Spox.com.
However, the report also claims that one other German outfit, plus several French sides are also monitoring the situation closely.
