The effective atomic numbers and electron densities of YBa2Cu3O7-delta superconductor at 59.5, 65.2, 77.1, 94.6, 122 and 136 keV were calculated by using the measured mass attenuation coefficients. Measurements were made by performing transmission experiments in a well-collimated narrow beam geometry set-up by employing Si(Li) detector with a resolution of 0.16 keV at 5.9 keV. These values are found to be in good agreement with theoretical values calculated based on XCOM data. The observed crystal structure of YBa2Cu3O7-delta superconductor is close to the theoretical structure. Z(eff) and N-el experimental values showed good agreement with the theoretical values for calcined and sintered YBa2Cu3O7-delta. (c) 2008 Elsevier B.V. All rights reserved.