Abstract Single crystals of triglycine sulphate (TGS) modified with La 3+, Ce 3+ and Nd 3+ have been grown from aqueous solutions by low-temperature solution growth method. The effect of rare earth ion dopants (La, Ce and Nd) on the ferroelectric properties of TGS is reported. Dielectric constant and dielectric loss have been measured for different frequencies. Dielectric measurements revealed that the dielectric constant of Ce-doped TGS increases rapidly at the transition temperature. Piezoelectric d 33 coefficient has been measured for the rare earth ions modified TGS crystals. Among the three dopants, Nd-doped TGS possesses low dielectric constant and high pyroelectric coefficient suggesting that this can be a potential material for infrared detectors.