The Mali international, 29, is hoping to complete his move in time to feature in Leeds' clash at Sheffield Wednesday on Saturday.
Kebe, who worked with Leeds boss Brian McDermott during Reading's 2011/12 promotion campaign, has found it difficult to nail down a starting place at Palace since joining in the summer.
"Kebe is on his way to Leeds as we talk," Palace boss Tony Pulis said at his Thursday morning press conference.
"That'll be a loan until the end of the season.
"Opportunities were limited here, because (Jason) Puncheon and (Yannick) Bolasie have done really, really well. Then you've got JT (Jerome Thomas) coming back."
Kebe left Reading in September and signed a three-year deal with Palace, who paid an undisclosed fee for the French-born midfielder.