In aqueous buffer, haemoglobin and myoglobin undergo direct electron transfer at bare and didodecyldimethylammonium bromide modified pyrolytic graphite electrodes. On immersion of the protein modified electrodes in methanol and ethanol, both proteins displayed a faradaic response, with E degrees' decreasing in comparison to the values obtained in aqueous buffer. Unlike haemoglobin, the E degrees' of myoglobin displayed a complex dependence on temperature, which was not observed with Hb, and displayed significant changes in Delta H degrees' and Delta S degrees'. (c) 2005 Elsevier B.V. All rights reserved.