The article presents test results concerning the welding procedure qualification of the production welding of heat-resistant cast steel GX40NiCrSiNb35-25 (1.4852) performed using filler metal WZ 25 35 Zr according to PN-EN ISO 14343. The welding procedure qualification test was performed in accordance with PN-EN ISO 11970. The test joint made using the TIG method (141) was subjected to non-destructive and destructive tests enabling the identification of the mechanical properties of the joint. The test results satisfied the requirements contained in PN-EN ISO 11970 and constituted the basis enabling the preparation of a related welding procedure qualification report.