Tin (Sn) substitution for titanium (Ti) was investigated in Ba6-3xNd8+2xTi18O54 (x = 1/2, 2/3, and 3/4) ceramics. A small amount (z < 0.1) of Sn substitution resulted in Ba6-3xNd8+2x(Ti1-zSnz)(18)O-54 solid solutions, and some secondary phases were observed with increasing Sn content. A small amount of Sri substitution improved the Qf value significantly, while, due to the formation of secondary phases, the Qf value degraded sharply for larger Sn content. The relative dielectric constant (epsilon(r)) decreased with increasing Sn-content, while the temperature coefficient of resonant frequency (tau(f)) generally decreased, although an obvious fluctuation was observed for x = 3/4.