The aim of this work is the formulation of a space marching method, which can be used to solve inverse axisymmetric heat conduction problems in thick-walled complex shaped elements. The method has to reconstruct the transient temperature distribution in a whole construction element based on measured temperatures taken at selected points inside or on the outer surface of the construction element. The developed method is applied for temperature identification in a heated steam gate valve. The presented method is tested using the measured temperatures generated from a direct solution. Transient temperature distribution obtained from the method presented below are compared with the values obtained from the direct solution. The presented method can be used for optimization of the power block's start-up and shut-down operations, may allow for heat loss reduction during these operations and can extend the power block's life. The presented method herein can be applied to monitoring systems that work in conventional as well as in nuclear power plants. (C) 2014 Elsevier Ltd. All rights reserved.