Nanoparticulate perovskite-type LnFe(0.9)Mg(0.1)O(3) (Ln = Nd, Sm, Gd and Dy) oxides were prepared by solgel method. X-ray diffraction was used to confirm the phase composition of the compounds. The materials exhibit p-type semiconductor behavior. Their sensitivity and selectivity towards ethanol gas were investigated. It was found that SmFe0.9Mg0.1O3-based sensor had the highest response and selectivity. It is a new potential gas sensing material. The great difference of conductance in air and ethanol gas was found and discussed in detail. (C) 2008 Elsevier B.V. All rights reserved.