A coupled electrochemical system and method for its use is disclosed, where a polyol feed, especially a biomass polyol containing feed is reduced in a reducing solution including HI and a metal ion capable of converting I2 to HI during polyol reduction to hydrocarbon or iodohydrocarbon products and where the metal ions are capable of electrochemical reduction so that the system can be run on a batch, semi-continuous or continuous basis. The system is capable of producing hydrocarbon solvent, fuels and lubricating oils.