The Mets purchased the contract of infielder Bobby Klaus from the Cincinnati Reds on July 19,1964. He was brought over to fill-in at second base for an injured Ron Hunt. He made his Met debut on July 30 as the starting second baseman and leadoff hitter, he went 0 for 4 with two strikeouts. He would than go on to hit safely in 7 out of his next 10 games, batting .302 over that span. When Hunt returned from his injury Klaus shifted to third base.
For the season Klaus appeared in 56 games and batted .244 with 2 home runs and 11 RBIs. Some of the highlights of his season included a 4 for 6 performance in the Mets 12-4 victory over the Phillies on August 16. On August 23 against the Cubs his 7th inning home run broke a 3-3 tie and paved the way for the Mets victory.
Klaus spent the entire 1965 season with the Mets appearing in 119 games, he hit just .191 with 2 home runs and 12 RBIs. The highlight of his season came on April 15 when he hit a 10th inning walk off home against the Houston Astro.
Following the season Klaus was traded to the Philadelphia Phillies along with Wayne Graham and Jimmie Schaffer for Dick Stuart. In 175 games for the Mets he hit .213 with 4 home runs and 23 RBIs.
While with the Mets Klaus wore number 6.
Bobby Klaus also played for the Cincinnati Reds in 1964.