Emmitt Thomas, 42, a veteran of two Super Bowls and four Pro Bowls in 13 seasons as a cornerback with the Kansas City Chiefs, yesterday was named an assistant coach of the Washington Redskins.

He joins Joe Gibbs' staff after five seasons on Jim Hanifan's staff at St. Louis, where he coached receivers. The Cardinals fired Hanifan after last season.

"I'm very proud and happy to be here," Thomas said yesterday. "We had five years of tough competition against the Redskins. The year before last, they broke our hearts in the last game." In that game, with the NFC East title at stake, the Redskins edged the Cardinals, 29-27.

Gibbs said yesterday that Thomas will be "in charge of research and development," which Gibbs explained as "stat work and film breakdown for the coaching staff . . . basically, a lot of the details and preparation for each week." Gibbs said a number of teams are adding to their staffs to help in week-to-week game preparation.

"We just felt that we couldn't let a person and coach of the high caliber of Emmitt pass us by," Gibbs said. "I've had great respect for him since his days at Kansas City, and we've certainly seen firsthand the success he's had the last few years at St. Louis."

The most prominent receiver Thomas worked with on the Cardinals was Roy Green, who established himself under Thomas as one of the best receivers in football.

Thomas is only the second coach added to the Redskins staff since Gibbs named his original group in 1981. Jerry Rhome was signed in 1983 after Dan Henning quit to become head coach at Atlanta.

A quarterback and receiver for Bishop (Tex.) College in 1963-65, Thomas coached Central Missouri State's defensive backfield for two years before joining the Cardinals.

"With so many teams talking to our assistants," said Gibbs, "if we ever have a vacancy Emmitt would be the perfect guy to fit in. He's coached both sides of the ball, and we like him."