Hydrogenated amorphous silicon (a-Si:H) thin films are presently used in several large-area thin-film applications. However, one major concern of a-Si:H is the fact that the stability of the material degrades when it is exposed to prolonged sunlight illumination. This effect, referred to as the Staebler-Wronski effect (SWE), is however reduced when using hot-wire (HW) deposited a-Si:H material with a low hydrogen concentration and favorable microstructure. In this thesis we report on the thermal stability of HW-deposited a-Si:H thin films, with different H-concentrations and bonding configurations, when exposed to elevated temperatures in excess of 100 "C.