The phase structure, microstructure and dielectric properties of Na0.5Bi0.5-xLaCu3Ti4O12 (NBLCTO) ceramics were investigated. La3+ substitution had a great influence on the phase structure and dielectric properties. The results showed that the pure phase could be more easily obtained when substituting La3+ for Bi3+. Under the same processing condition (970 degrees C for 7.5 h) and measuring condition (10 kHz around room temperature), NBLCTO ceramics with x = 0.10 possessed the highest permittivity (1.02 x 10(4)) and lowest dielectric loss (0.022). The obtained NBLCTO ceramics with x = 0.10 also had good frequency stability and good temperature stability (-1.87% to +3.27%) from -60 degrees C to 120 degrees C at both 1 and 10 kHz. Complex impedance results revealed that the grain resistance R-g was 7.18 Omega cm and the grain boundary resistance R-gb was 1.19 x 10(6) Omega cm. (C) 2011 Elsevier Ltd. All rights reserved.