Periodic mesoporous organosilica containing ethylene bridges have been synthesized and subsequently modified introducing sulfonate groups. The structural and physicochemical properties of the materials were characterized by nitrogen physisorption, FTIR spectroscopy and XRD. Their hydrophilic/hydrophobic behavior was studied by water sorption, while the hydrothermal stability of the sulfonated material and unmodified material were determined by multi-cycle stability tests. The sulfonated sample showed an improved hydrophilicity with a tripled water uptake at p/p0 = 0.4. N2 and water sorption measurements before and after the cycle stability test revealed that the sulfonated sample lost capacity due to the reduced porosity. However, the overall hydrophilicity of the material even increased, which we ascribe to the hydroxylation of the organosilica surface. These findings indicate that PMOs containing ethylene bridges with a suitable hydrophilic functionality can be a promising adsorbent material for desiccant-based cooling system (DCS).