Governor Aswin Kwanmuang oversaw the launch of the service, which runs east from Wat Si Bun Rueang pier in Bang Kapi district to Minburi District Office pier.
Aswin said the new route will be help people who want to commute from Minburi to inner-city areas.
The service is operated by the TTA Chao Phraya Express Boat Consortium and features 12 electric boats with zero emissions and quieter engines than diesel-powered vessels, said the governor.
Each boat has 40 regular seats plus two for wheelchair users and two bike racks for cyclists. The fare is free until the end of August, after which a ticket will cost 15 baht for the whole route.
Saen Saep’s electric boats run from 5.30am to 8.30pm on weekdays and 6am to 7pm on weekends and holidays. The Wat Si Bun Rueang-Minburi extension is 10.5 kilometres long with a travel time of 50-60 minutes. It features 12 stops: Wat Si Bun Rueang, Phrom Mitr Phittaya School, Paseo Mall, Serithai 26, Rahas Canal, Muban Rom Sai, Darul Abeedeen Mosque, Lo Lae Yai Community, South Bangchan Watergate, North Bangchan Watergate, Minburi Market, and Minburi District Office.
City authorities forecast 600-1,000 passengers will ride the route every day.