In all the cases, sugar yields above 40% (percentage of sugar released of total sugar present in the microalgae) were obtained. Even when no acid was used, the steam explosion pretreatment resulted in the release of a considerable amount of monosaccharides. Besides, increasing the temperature when acid catalysis is not used, from 120 °C to 150 °C, had no effect on the total amount and distribution of the resulting sugars in solution.