K X-ray fluorescence cross-sections of Cu, Y and Ba elements were measured in CuO, Y2O3, BaCO3 Compounds and YBa2Cu3O7-delta superconductor samples (nonreacted agent, calcined and sintered states). A superconductor sample of YBa2Cu3O7-delta was prepared by using a solid-state reaction technique. The samples were excited by gamma rays of energy 59.5 keV from a Am-241 radioisotope source. The Cu, Y and Ba K X-ray intensities counted with a Si(Li) detector were measured in different solid-state conditions. The obtained values of K X-ray fluorescence cross-section were compared with the theoretical values of pure Cu, Y and Ba elements. We found that the K X-ray fluorescence cross-section of Cu, Y and Ba in YBa2Cu3O7-delta sample is changed in different solid-state conditions, depending on the mixture (nonreacted agent), calcined and sintered states. (c) 2008 Elsevier Ltd. All rights reserved.