Micro gas sensors fabricated with WO3 loaded with and without a noble metal and/or NiO as a sensing material were operated in dynamic temperature modulation mode with sinusoidal modulation of Pt-heater voltage [low voltage: 0 V for RT, maximum voltage: 0.6 V (for 150 ℃)– 1.6 V (for 400 ℃), period: 6 s], and their acetone-sensing properties were investigated in dry and wet air. The WO3 sensor showed negligible dynamic responses to acetone and H2, but the loading of a noble metal onto the WO3 markedly improved the dynamic responses, particularly to acetone in dry air. Among all the 0.5 wt% noble-metal-loaded WO3 (0.5N/WO3, N: noble metal) sensors tested, the 0.5Pt/WO3 sensor showed the largest dynamic response to acetone in dry air, while the dynamic response to acetone was largely decreased by the addition of moisture into the gaseous atmosphere. The loading of NiO onto WO3 and 0.5Pt/WO3 improved the dynamic response to acetone of the WO3 and 0.5Pt/WO3 sensors, and the 1.0 wt% NiO-loaded 0.5Pt/WO3 sensor showed the largest dynamic acetone response and dynamic acetone selectivity against H2. These acetonesensing properties of the sensors operated in dynamic temperature modulation mode were superior to those of the ones operated in static constant temperature mode, possibly because of acetone and/ or its partial oxidation products adsorbed on the oxide surface at low temperatures and their abrupt catalytic combustion with oxygen adsorbates at high temperatures.