Phase composition of the murataite-based ceramics containing 10 wt.% of mixed oxides simulating rare earth/actinide (REE/An) and actinide (An) fractions of high level waste (HLW) was studied. The ceramics were prepared by melting of oxide mixtures in Pt ampoules in air at ∼1500 °C. Ceramics with REE/An and An fractions surrogates are composed of predominant murataite-type phases and minor extra phases: perovskite and crichtonite. Three murataite-related phases with five- (5C), eight- (8C), and three-fold (3C) elementary fluorite unit cell are present in these ceramics. These phases form core, intermediate zone, and rim of the murataite grains, respectively. They are predominant host phases for the rare earth elements and uranium whose concentrations are reduced in a row: M-5C>M-8C>M-3C. Appreciate fraction of Ce, Nd, and Pu may enter the perovskite phase. In the An-Gd ceramic perovskite and murataite were found to be predominant and secondary in abundance phases respectively.