Systems and methods are provided for increasing the yield of products generated during co-processing of biomass oil in a fluid catalytic cracking (FCC) system. The systems and methods can allow for increased yield by reducing or minimizing formation of carbon oxides, gas phase products, and/or coke yields during the co-processing. This can be achieved by adding a hydrogen-rich co-feed to the co-processing environment. Examples of hydrogen-rich co-feeds include high hydrogen content vacuum gas oil co-feed, high hydrogen content distillate co-feed, and/or high hydrogen content naphtha co-feed. Additionally or alternately, various types of fractions that contain a sufficient amount of hydrogen donor compounds can be used to reduce or minimize carbon oxide formation.