Heteroepitaxial LaFeO3 (1 1 0) thin films with a thickness of 150 nm were grown on LaAlO3 (0 0 1) by reactive sputtering in an inverted cylindrical magnetron geometry. Equilibrium conductivity was measured as a function of partial pressure of oxygen at T = 1000 degreesC, and log sigma plotted vs. log P(O-2) showed a minimum in conductivity for P(O-2) = 10(-11) atm and a linear response between 10(-10) and 1 atm. This linear response makes thin films of LaFeO3 a promising material for oxygen sensor applications. We have also measured the time response of the film conductivity upon an abrupt change in the partial pressure of ambient oxygen from 10(-2) to 10(-3) atm, which was determined at 60 s for T = 700 degreesC and <3.5 s at T = 1000 degreesC. (C) 2003 Elsevier Ltd. All rights reserved.