DTA, d.c. conductivity and thermoelectric power of the compounds RMnCl4, RCoCl4 and RMn0.5Co0.5Cl4 (R = H3N-(CH2)8-NH3) were measured over a temperature range of 300–500 K. Both the DTA and the d.c.-conductivity results show the presence of many phase transitions in each of the complexes investigated. The conductivity results are explained on the basis of an electron-hopping mechanism. The effect of γ-irradiation on the conductivity data and the type of crystal phase are investigated and discussed.