Kaeding injured his groin during last Sunday's 20-17 loss at St. Louis that dropped the Chargers to 2-4.
To make roster room for Brown, the Chargers released third-string quarterback J.T. O'Sullivan.
Brown, a 12-year veteran, was the Houston Texans' kicker from 2002 to 2009 before being released in September.
"He's experienced," Chargers coach Norv Turner said. "He's been very productive. He kicked awfully well today, and he's kicked at a high level in this league."
Brown has made 252 of 326 career field-goal tries (.773) and scored 1,103 career points. In 2007, Brown tied an NFL single-game record by making three field goals longer than 50 yards, including a game-winning 57-yarder as time expired against the Miami Dolphins.
Turner said there's a chance Kaeding could miss more than just Sunday's game.
Kaeding didn't practice Wednesday. Also sitting out for the Chargers were linebacker Larry English (foot), wide receiver Legedu Naanee (hamstring), wide receiver Malcom Floyd (hamstring), tight end Antonio Gates (toe) and running back Ryan Mathews (ankle).
"If you miss Wednesday's practice, obviously it gets harder," Turner said.
Turner said Monday that he hoped Gates could play this week, but Floyd's injury probably is bad enough to keep him out of Sunday's game.
The coach said he expects Mathews to practice Thursday.
The Chargers also released tackle Ryan Otterson from the practice squad and signed wide receiver Gary Banks.
Copyright 2010 by The Associated Press
