Shunt capacitive RF MEMS switches have been developed using III-V technology and employing (tantalum pentoxide) Ta2O5 thin films as dielectric layers. In order to evaluate the potential of the Ta2O5 thin films for the considered application, the compositional, structural, and electrical characterization of the deposited films has been performed, demonstrating that they are good candidates to be used as dielectric layers for the fabrication of RF MEMS switches. Specifically, Ta2O5 films are found to show a leakage current density of few nA/cm2 for  MV/cm and a high dielectric constant of 32. Moreover, the charging process has been investigated, finding that it follows a stretched exponential law. The fabricated switches show actuation voltages in the range 15–20 V, an insertion loss better than −0.8 dB up to 30 GHz, and an isolation of ~−40 dB at the resonant frequency which is around 25 GHz.