Flow boiling and saturated pool trailing were studied in water, and in ethylene glycol and aqueous antifreeze solutions. Boiling took place from an electrically heated cast iron surface at pressures close to atmospheric. In the flow boiling tests, velocities and subcoolings were varied up to 3 m/s and 36°C respectively, and effects of changes in flow passage geometry were examined. In 50 weight percent antifreeze mixtures the pool boiling critical heat flux increased relative to pure ethylene glycol in aqueous solution. Both critical heat flux and heat transfer coefficients decreased as percent water in the mixtures tested was reduced.