On the timescale of solid oxide fuel cell (SOFC) system lifetime requirements, the thermodynamically predicted low-level substitution of chromium on the B-site of (La,Sr)MnO3 could be a source of cathode degradation underlying more overt and well-known chromium poisoning mechanisms. To study this phenomenon in isolation, electronic conductivity (sigma) and electrochemical oxygen reduction activity of the (La0.8Sr0.2) 0.98CrxMn1-xO3 model series (x = 0, 0.02, 0.05 or 0.1) were measured in air between 850 and 650 degrees C. Depending on the extent of chromium substitution and the measurement temperature, electrochemical impedance spectroscopy (EIS) results could be deconvoluted into a maximum of three contributions reflecting possible limiting processes such as oxide ion transport and dissociative adsorption. Chromium substitution resulted in lowered a (from 174 S cm(-1) (x = 0) to 89 S cm(-1) (x = 0.1) at 850 degrees C) and a steady rise in associated activation energy (E-a) (from 0.105 +/- 0.001 eV (x = 0) to 0.139 +/- 0.001 eV (x = 0.1)). From EIS analyses, ohmic and polarisation resistances increased, whilst E-a for the overall oxygen reduction reaction also increased from 139 +/- 0.04 eV (x = 0) to 1.48-1.54 +/- 0.04 eV upon chromium substitution. (C) 2014 Elsevier B.V. All rights reserved.