Ca doping of YBa2Cu3O7-delta (YBCO) is well known to enhance the critical current density in large-angle grain boundaries for example of bicrystals. However, up to now no data are available on microwave properties of epitaxial Ca-doped YBa2Cu3O7-delta thin films on r-plane sapphire with CeO2 buffer layer. Therefore, first results are presented for large-area pulsed laser deposition (PLD) grown CaxY1-xBa2Cu3O7-delta films on 3-in. diameter sapphire wafers. The PLD process is optimised for undoped YBCO thin films and shows high reproducibility for YBCO. The microwave surface resistance R-s at 8.5 GHz of Ca-doped YBCO (x = 0.1) thin films shows clear reduction (up to 20%) with respect to that of YBCO for temperatures from about 20-50 K. In addition, microwave surface resistance R-s of Ca-doped YBCO is lower than that of YBCO even for enhanced microwave surface magnetic field up to about 20 mT for temperatures 20 and 40 K. (C) 2003 Elsevier Ltd. All rights reserved.