This paper reports the results of an experimental program on sustainable cementitious composites made with microencapsulated phase change materials (MPCMs) to enhance thermal energy storage. The study focuses on the development and evaluation of cement-based mortars using river sand as fine aggregate and incorporating various MPCM contents (0%, 10%, 20%, and 30% by total mortar volume). The main objective was to investigate the mechanical and durability performance of these mixtures, along with the thermal behavior. Tests conducted included true and bulk density, particle size distribution and water absorption measurements. Mechanical testing was carried out to evaluate the influence of MPCM on compressive and bending strengths. The MPCM used in the study has an apparent solid density of 0.80 g/cm3 and a latent heat of 160 kJ/kg. According to the results, mechanical strength decreased with increasing MPCM content, and in the 30% MPCM mix, values dropped to below 50% of the reference. Regarding durability, water absorption in the 20% MPCM mix was lower than the reference, but increased at 30%, exceeding the reference value. This trend may be attributed to matrix compactness disruption due to the high MPCM content. Furthermore, the average mixture (20% MPCM) demonstrated significant thermal energy storage capacity compared to the reference.