A nontoxic fuel cell engine coolant which has an electrical resistivity of greater than 250 kOhm-cm, a boiling point of greater than 90.degree. C., a freezing point of less than -40.degree. C., a thermal conductivity of greater than 0.4 W/m-k, a viscosity of less than 1 cPs at 80.degree. C., a viscosity of less than 6 cPs at 0.degree.C., a heat capacity of greater than 3 kJ/kg-K, and which is compatible with current cooling system materials.