The results of an experimental investigation of heat exchange during secondary cooling of the inner surface of a hollow cylindrical strand (tube blank) on a horizontal type continuous casting machine are presented. It was found that the air-water mixtures used give heat exchange rates 3-5 times greater than those with a single phase air stream. The consumption of the air-water system is considered. The functional relation between the heat exchange coefficient and tube length can be used in mathematical modelling of the solidification process.