Detection of volatile organic compounds (VOCs) at room temperature in an ambient environment is highly desired, but still a distant function for gas sensor materials. Usually, metal oxide semiconductors (MOS) are used in chemical gas sensors which operate at elevated temperatures between 150-300 °C. The high temperature possesses security risks as well as causes high power consumption. Alternatively, MOS gas sensors can be activated by light that exceeds their band gap energy at room temperature. Photoillumination has been used with MOS for the detection of different gases (O2, H2, CO) as well as VOCs (ethanol, formaldehyde). However, most of these have been reported in a dry environment. Previously, we have reported on a UV-active gas sensor prepared from ultra-fine TiO2 nanoparticles, that is capable of high magnitude gas response in ambient humidity as high as 40% [1]. Now we expand on this concept by examining the gas sensing properties of TiO2 thin films prepared from ultrasmall TiO2 nanoparticles doped with Nb, Hf and Ta. Herein we show that doping with electron acceptor dopants increases the room temperature gas response from several times to several orders of magnitude.