In this work, the thermal effects of a tunable matching network (TMN) based on micro electro mechanical systems (MEMS) are investigated. A reconfigurable power amplifier (PA) is proposed based on a TMN. The thermal effects are modeled and their influence on the linearity of the PA are addressed. The study is aided by a behavioral model of the capacitive MEMS switch which has been extended in order to include the thermal effects that raise due to power dissipation at the MEMS's membrane. The PA architecture is based on a commercial process design kit and the MEMS switch is based on the geometry and material characteristics of an available component.