The LaGaO 3 -NdGaO3 pseudobinary system was investigated in the concentration range 0-53 at.% Nd by means of X-ray structural and phase analysis. The La 1 - x Nd x GaO 3 solid solutions exist in the whole investigated concentration region. The lattice constants change with increasing Nd content: a decreases from 5.52266(6) to 5.46754(7) 9, and c from 7.7713(1) to 7.74241(9) 9, whereas b increases from 5.49047(7) to 5.49118(6) 9. There are four ranges of La 1 - x Nd x GaO 3 solid solutions characterized by different relations between the Perovskite-like cell parameters: I (0<x<0.225) with a p >c p >b p ; II (0.225<x<0.32) with a p >b p >c p ; III (0.32<x<0.39) with b p >a p >c p ; and IV (0.39<x<1) with b p >c p >a p .