Katz said he was drawn to Beth Emek by the "really fine congregation."
"Its congregants are eager and willing, with a serious concern for study of Torah, and very lovely and inspiring services," he said.
The Beth Emek board conducted an extensive search and interview process, said Congregation President Skylar Cohen.
"It quickly became clear that Rabbi Katz is the right choice as our spiritual leader," Cohen said.
His contract is just under two years, and the board hopes to begin its search for a permanent rabbi after the first of the year, Cohen added.
Katz, 58, moved in August to Pleasanton from San Diego, where he served for the past three years at Congregation Beth Israel. Previously, he spent more than 20 years as rabbi at congregations in New York and Virginia, and several years as a temple educator.
He was ordained at Hebrew Union College, New York, in 1981, and has master's degrees in both Hebrew Education and Hebrew Letters, plus earned bachelor's and master's degrees from Northwestern University in Theatre, with an emphasis in direction. Katz is also a past president of the New York Area Reform Rabbis, and has been a member of influential Reform Judaism practice and liturgy committees.
"I look forward to helping lead Congregation Beth Emek into the next phase of its growth," Katz said. "Congregants and the broader Tri-Valley community have already extended a warm welcoming hand, and my family is eagerly anticipating this wonderful opportunity."
He noted that Beth Emek has a vibrant religious school and Midrasha, or program for Jewish teens to explore their religion and heritage.
Katz and his wife Nancy, an artist, are the parents of two grown children, Emily and Ben.
Congregation Beth Emek's membership numbers about 200 families. It moved from Livermore into its new facility on Nevada Street in Pleasanton in 2005.
Rabbi Richard Winer, who had headed Beth Emek fulltime since 1998 after three years part time, relocated to Temple Beth Israel in Fresno at the beginning of the summer.
Katz said he plans to "strengthen the congregation to carry on all the good things that our previous rabbi has accomplished."