Love wave sensors coated with mesoporous sensitive layers have shown good sensitivity and short-time response for volatile organic compounds (VOCs) and heavy metal detection. This chapter describes the Love wave device. The Love wave sensing principle is based on the perturbation of a guided shear horizontal surface acoustic wave. The chapter then discusses mesoporous materials and environmental ellipsometric porosimetry (EEP). It presents the experimental device, combining acoustic wave and EEP, and the results. Simulations of Love wave propagation have been performed and shear modulus variations of a mesoporous titania film have been determined with a maximum variation of 2.1 GPa during the desorption. Finally, the possible explanations of this nonlinear response are discussed, regarding the porous nature of the film and its specific fabrication process.