Kempers 1988 professional tennis player. He played the first two years on the ATP Challenger Tour, to be able to initially show no greater success. In October 1990, he reached with his compatriot Richard Krajicek the final of the ATP tournament in Athens, which, however, was lost. In 1991, he was able to win with Jacco Eltingh in Palermo his first doubles title. Overall, he celebrated during his career four doubles titles on the ATP World Tour, were added seven more doubles titles on the ATP Challenger Tour. Its highest listing in the tennis world ranking he reached in 1994 with position 253 in single and in 1998 with position 42 in doubles.
His best individual result at a Grand Slam tournament was reaching the first round of Wimbledon 1996., Where he lost to Brett Steven smooth in three sets. This was also his only qualification to a Grand Slam singles tournament. In the doubles competition, he reached the second round in each of the Australian Open, the French Open and Wimbledon. In addition, he stood in the mixed twice in the second round of the U.S. Open.