The cooling and solidification of continuous casting slabs were analysed by a new mathematical model, in which heat transfer coefficients on the slab surface both in the mould and in the spray zone were deter-mined semi-empirically from operational data. The effect of air gap between the slab surface and the mould was taken into account in the estimation of the heat transfer coefficient, and the point of complete sepera tion of the slab surface from the mould was determined as a function of the withdrawal rate. The heat transfer coefficient in the spray zone was obtained from modification of an empirical formula on spray cooling of steel plates. The results of analysis made clear the effects of operational conditions, that is, the solidification profile depends mainly on the withdrawal rate, while the surface temperature is affected much more by the water ratio in the cooling zone.