<P><B>Abstract</B></P> <P>Bio-H<SUB>2</SUB> and bio-CH<SUB>4</SUB> production from food waste in a two-stage temperature phased system were investigated to determine the effects of digestate recirculation on energy efficiency and process stability. Different recirculation ratios (RR), i.e. 0.3, 0.5, and 1.0, were tested. Maximum H<SUB>2</SUB> production of 3 L-H<SUB>2</SUB> L<SUP>−1</SUP>d<SUP>−1</SUP> and yield of 135 L-H<SUB>2</SUB> kg<SUP>−1</SUP>VS<SUB>in</SUB> were achieved for an RR of 0.3 at HRT 5 d and OLR of 18 kg-VS m<SUP>−</SUP>³d<SUP>−1</SUP>. The RR of 0.3 was also the best for producing CH<SUB>4</SUB> and gave results of 2.9 L-CH<SUB>4</SUB> L<SUP>−1</SUP> d<SUP>−1</SUP>, i.e. 510 L-CH<SUB>4</SUB> kg<SUP>−1</SUP>VS<SUB>in</SUB> at HRT 9 d and OLR of 5.7 kg-VS m<SUP>−</SUP>³ d<SUP>−1</SUP>. The energy recovered from the recirculation process increased the H<SUB>2</SUB> production by 8% and decreased the CH<SUB>4</SUB> production by 3%; the total energy production did not change. Digestate recirculation in comparison with a no-recirculation system reduced the need for alkali addition to maintain pH in the H<SUB>2</SUB>-reactor by 54%.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Two-stage AD process was positive for food waste digestion. </LI> <LI> Digestate recirculation in the first stage reduced alkaline addition by 54%. </LI> <LI> Optimal recirculation ratio was 0.3 </LI> <LI> The hydrogen energy obtained from FW was improved by 8% with recirculation. </LI> <LI> Digestate recycling did not increase the overall energy yield. </LI> </UL> </P>