Plug Power Inc., a Latham, N.Y.-based fuel cell technology company, announced this afternoon that it has acquired the assets of Spokane Valley-based ReliOn Inc., developer of fuel-cell stack technology and fuel cell systems, in a transaction valued at about $4 million.

Teal Vivacqua, a spokeswoman for Plug Power, says the company plans to maintain the Spokane office and will continue to use the ReliOn brand name on its products.

Plug Power plans to add key personnel from ReliOn, primarily in sales and engineering, but it hasn’t determined yet how many employees will be retained here, Vivacqua says. She says she didn’t have available ReliOn’s current employment, but in December 2013, the Journal of Business reported that 53 people worked for the company.

Plug Power said in a press release that it currently has more 150 U.S. patents related to fuel-cell system design, fuel processing, fuel dispensing, energy storage, and controls. The acquisition adds 34 fuel-cell patents to the company’s portfolio.

ReliOn has operated as an independent, investor-backed venture since Spokane-based power company Avista Corp. spun it off in 2003.