(Ba1–xNdx)(Ti1–y–x/4Cey)O3 (BNTC) ceramics with a pseudo-cubic structure were prepared using the mixed oxide method. The dielectric-peak temperature decreased rapidly at a rate of −27°C/at.% Nd for BNTC with y = 0.05. BNTC with x = y = 0.05 (BN5TC5) exhibited a high-permittivity diffuse phase transition behavior but had a higher dielectric loss (tan δ = 0.219). A high-permittivity (ε'RT = 14100) and low-loss (tan δ = 0.014) X7V ceramic was achieved by means of the addition of 1 % Ce in BN5TC5. A g = 2.509 electron spin resonance (ESR) signal associated with Ce3+ Kramers ions confirmed the existence of mixed valence states of Ce3+/Ce4+. A g = 2.151 ESR signal of Nd3+ can be detected at room temperature after these ceramics were preserved over a long period of time.