Dielectric ceramics based on Ca9Nd2W4O24 (CNW) and Ca9Sm2W4O24 (CSW) were synthesized using solid state reaction method. X-ray diffraction and EDAX analysis showed that phase purity could be achieved when ceramics were calcined at 1200 degrees C and sintered at 1450 degrees C. Dielectric properties of CNW and CSW ceramics were investigated with measurement performed at radio as well as microwave frequency range. The microstructure and thermal properties of the CNW and CSW ceramic samples were also investigated. (C) 2014 Elsevier B.V. All rights reserved.