The invention relates to the preparation of carboxylic acid esters compounds, biodiesel (B) from microalgae, for use as a biofuel for compression type ignition. The objective is achieved through a hydroesterification process of a microalgae biomass (MU) comprising a hydrolysis stage and the esterification stage by means of heterogeneous catalysis. The wet microalgae biomass (MU) is the result of a process of cultivation concentration and is hydrolyzed directly in a hydrolysis column (20). Fatty acids (C), water (A) and raw glycerin (G) are obtained following the hydrolysis. The fatty acids (C) are esterified by reactive distillation in the presence of an impregnated heterogeneous catalyst (I).