•Aqueous phase from algal liquefaction was recycled as a reaction medium for HTL.•The oil yield increased significantly when recycling the aqueous phase.•Recycling of aqueous phase led to marked increases in oil yield from catalytic HTL.•The oil quality from aqueous phase recycling was not scarified for improving yield. In this study, the aqueous phase obtained from catalytic/non-catalytic hydrothermal liquefaction (HTL) of Chlorella vulgaris was recycled as the reaction medium with an aim to reduce water consumption and increase bio-crude oil yield. Although both Na2CO3 and HCOOH catalysts have been proven to be effective for promoting biomass conversion, the bio-crude oil yield obtained from HTL with Na2CO3 (11.5wt%) was lower than that obtained from the non-catalytic HTL in pure water at 275°C for 50min. While, the HCOOH led to almost the same bio-crude yield from HTL (29.4wt%). Interestingly, bio-crude oil yield obtained from non-catalytic or catalytic HTL in recycled aqueous phase was much higher than that obtained from HTL in pure water. Recycling aqueous phase obtained from catalytic HTL experiments resulted in a sharp increase in the bio-crude oil yield by 32.6wt% (Na2CO3-HTL) and 16.1wt% (HCOOH-HTL), respectively.