Oakland, Calif. ? Free-agent slugger Frank Thomas agreed to a $500,000, one-year contract with Oakland on Wednesday, giving the Athletics the big bat they’ve been searching for in the middle of their lineup.

Thomas, a two-time American League MVP who has been slowed by injuries in recent years, can make an additional $2.6 million in bonuses based on plate appearances and not hurting his left foot. He played his first 16 seasons with the Chicago White Sox, who won their first World Series title since 1917 last season.

The low-budget A’s have spent recent offseasons losing big-name players such as Jason Giambi, Miguel Tejada, Johnny Damon, Tim Hudson and Mark Mulder. But after missing the postseason for the second straight year following four consecutive trips to the playoffs, Oakland general manager Billy Beane has added Thomas and Milton Bradley to a lineup that struggled to score runs at times last season – and done so without losing anyone of significance.

Beane had been interested in acquiring Thomas for months, and the deal reportedly was in the works for some time. Thomas will be the A’s primary designated hitter and join Eric Chavez and Bradley in the heart of Oakland’s order.

Hobbled by leg injuries for the second straight season, the 37-year-old Thomas hit .219 with 12 homers and 26 RBIs in 34 games in 2005. He played only 74 games in 2004 following a 42-homer season the previous year.