Compounds of the ternary oxides class with formulae MgLayMoO(7) and CaLa2MoO7 were synthesized by the citrate method. According to the SEM and X-ray analysis data the samples are referred to pyrochlore with a tetragonal (MgLa2MoO7) and monoclinic (CaLa2MoO7) crystal lattice. At the temperature of 900 degrees C the compound CaLa2MoO7 is subjected to phase transition from the monoclinic crystal system to the cubic one. According to the differential thermal analysis data, this transition occurs through the intermediate states characterized by non-monotonic changes of lattice parameters of the unit cell. In general, the compounds are characterized by minor structural distortions compared with the cubic structure of pyrochlore. (C) 2015 Elsevier B.V. All rights reserved.