Abstract: Disclosed herein is a microwave dielectric ceramic composition which comprises as the main ingredient, a composition represented by xMgTiO.sub.3 .multidot.(1-x)CaTiO.sub.3 (0.93.ltoreq.x .ltoreq.0.95), to which 3-9 wt % of ZnO, 2-4 wt % of Ta.sub.2 O.sub.5, 1-6 wt % of Nb.sub.2 O.sub.5, 0.1-6 wt % of MnO.sub.2, 3-12 wt % of Al.sub.2 O.sub.3 or 3-12 wt % of Co.sub.2 O.sub.3 to xMgTiO.sub.3 .multidot.(1-x)CaTiO.sub.3. And the microwave dielectric ceramic compositions have a Qu value in the range of 3000 to 4600 (at 6 GHz), a temperature coefficient of the resonance frequency (.tau.f) in the range of -10 to +10 ppm/.degree.C. and relative dielectric constant (.epsilon..sub.r) in the range of 18 to 22. The dielectric ceramic compositions are capable of reducing .tau.f approximately to zero or optionally and stably controlling .tau.f to a desired value both to positive and negative sides around zero as the center while maintaining .epsilon..sub.