A study of heat transfer in a two-pass internal cooling passage of gas turbine airfoils is presented. Heat transfer measurements were performed with a transient technique using thermochromic liquid crystals. Flow temperature measurements along the channels are used to evaluate the heat transfer distribution. Thereby two methods are applied. The first uses the measured temperature histories directly and applies the superposition method for data evaluation. The second method analyses first the fluid temperature data using a simplified model and relates them to the average flow temperature at a given location. The results of both methods are compared. (C) 2004 Elsevier Ltd. All rights reserved.