The city's Vice Mayor serves as mayor when Mayor Jerry Thorne is out of town and at other times at Thorne's request.
Pentin, who was elected to the council in 2012, is one of only two on the council not affected by this year's municipal election on Nov. 4.
Cook-Kallio's eight years of service end in November because of term limits. She could seek election as mayor again after an unsuccessful try in 2012.
Thorne, who was elected mayor in 2012, has announced he will seek re-election to that post in November. In Pleasanton, mayors are elected every two years with four terms, or eight years, allowed under the term-limits law.
Councilwoman Kathy Narum also has announced she will seek re-election in November. She was elected last May in a special mail-in ballot election to fill Thorne's unexpired two-year term when he was elected mayor. Narum's current service on the council is not covered under the term-limits law, which means she could serve two full four-year terms on the council if re-elected.
Councilwoman Karla Brown, who was elected to a four-year terms on the council in 2012, has until 2016 before facing re-election.
In other action, members of the council were assigned to sit on boards or serve in a liaison capacity for 31 separate local, regional and council committees. Thorne will continue to represent Pleasanton as one of three mayors on the governing board of directors of TV30 community television and on the Alameda County Mayors' Conference.