This invention refers to a procedure for obtaining fatty acids of pharmacological and nutritional interest that comprises the steps of feeding a gas comprising CO2 into a reactor that contains a culture that comprises at least one species of microalgae capable of photosynthesis, the process of photosynthesis by the species of microalgae from the CO2 supplied, producing a biomass that contains a general formula (I) compound:extraction of the general formula (I) compound from the biomass obtained and concentration and/or purification of this compound.