Abstract: This study presents the evaluation of the alkaline stabilization of the biosolids results of the operation of a treatment plant of wastewater to improve the fisiochemical quality. Two alkalizing, the alive cal (CaO) and the hydratedcal (Ca(OH)2), characterizing two experiments, each one form by dose of 15 and 25% in proportions weight to weight of biosolid duplicated with a treatment witness without application of alkalizing, totalizing ten treatments. The treatment of biosolid with dose of 15% of hydratedcal (Ca(OH)2), accomplishing the previous period of dryness in a month, got better results according not to modifying drastically the content of organic matter and macronutrients (N, P and K) and accomplishing the maximum values of humidity.