Methylsiloxane-based spin-on-glass (M-SOG) has been applied to a polycrystalline silicon thin-film transistor (TFT) on a 40 mu m-thick flexible metal foil as a gate dielectric and planarization layer as well. Triple spin coatings and curing of M-SOG layers reduce the surface roughness of the metal foil from 800 to 56 angstrom. The p-channel metal-induced crystallization of a-Si using a cap TFT using M-SOG on a metal foil exhibited a field-effect mobility of 51.1 cm(2)/V s, a threshold voltage of -4.3 V, and a minimum off-state current of <1.74 x 10(-12) A/mu m at V-ds = -0.1 V. The poly-Si TFT was found to be stable against a negative gate-bias stress. Therefore, the low-cost, low-temperature polycrystalline silicon TFT can be applied to make flexible displays. (C) 2008 The Electrochemical Society.