Supercritical methanol was used for one put biodieselproduction from microalgae biomass. Fatty acid methyl esters (FAMEs) hydrocarbons, and oxygenates were produced in catalytic and non-catalytic procedures in the presence and absence of subcritical water. The CaO nanoparticles were synthetized using photochemical method on TiO2. Addition of catalyst and water to supercritical methanol could increase total product yield up to 51.6%, FAMEs yield up to 28.1%, hydrocarbons yield up to 2.5 times, and oxygenates yield up to 3.8 times. No CaO was detected in products and no color change occurred for product over time. The effects of catalysts and subcritical water on quality and quantity of products were described using reaction mechanisms. Accordingly, it can be proposed that water in subcritical condition dissolves cell wall of biomass and facilitates mass transfer of bio-oil to catalyst surface. In addition, it produces intermediates on catalyst surface that can accelerate FAMEs and oxygenates production.