Ba-2(Zn0.5Ti0.5X)O-6 compounds from the general ABO(3) perovskite family were synthesized by the classical solid-state route for X = Nb and Ta with various A/B ratios (1.005, 1 and 0.995). After the calcination step at 1100 degrees C, both compounds (X = Nb and Ta) contain mainly the cubic disordered 'Ba-2(Zn0.5Ti0.5X)O-6' phase but traces of BaTiO3 and secondary phases are often detectable. Nevertheless, after the sintering stage at higher temperature (from 1300 to 1500 degrees C) and for all A/B ratios investigated, Ti enters into the cubic perovskite structure, resulting in the formation of a unique 'Ba-2(Zn0.5Ti0.5X)O-6' phase. Attractive dielectric properties have been measured on the tantalum-based compound for A/B = 0.995 (Q similar to 2000 at 7.4 GHz and epsilon = 39.6) as well as on the niobium-based phase for A/B = 1.005 (Q similar to 2200 at 6.1 GHz and epsilon = 54.8). All these characteristics were confirmed at 1 MHz and a linear dependence of the permittivity versus temperature from -60 to 180 degrees C has also been evidenced for both formulations. Sinterability, dielectric properties and microstructure of such compounds are discussed with respect to the stoichiometry. (c) 2005 Elsevier Ltd. All rights reserved.