Thick film of silver decamolybdate (Ag6Mo10O 33) was screen printed and thin film of chromium titanate Cr 1.8Ti0.2O3+δ was laser deposited on alumina substrates. Morphological features of the films were characterised and ammonia sensing properties were studied. Resistance of Ag6Mo 10O33 thick films decrease on introduction of NH 3 gas and these films were capable of sensing 2 ppm of ammonia in air at 578 K. Cr1.8Ti0.2O3+δ thin films could sense 20 ppm of ammonia in air at 673 K, which exhibited increase in resistance towards NH3 gas. © 2008 Institute of Materials, Minerals and Mining.