Dielectric and nonlinear properties of a binary compound derived from Ca2Cu2Ti4O12 were greatly improved by doping with Zn2+ to deliberately create CaCu3-xZnxTi4O12/CaTiO3 composites. Ca2Cu1.8Zn0.2Ti4O12 composition can exhibit an enhanced epsilon', similar to 6,513, with a strong reduction in tan delta to similar to 0.015 (at 1 kHz). The nonlinear coefficient and breakdown field strength were significantly enhanced. The dielectric and nonlinear properties were described based on the effect of Zn2+ substitution on electrical response of internal interfaces.