Structure refinement of power x-ray diffraction data shows that when x changes from 0.01 to 1.0, the crystal lattice is La2-xSrxNiO4 has cation (La, Sr) and anion O(1) deficiency. It agrees with the prediction of the values of temperature factor (B). In addition, the content of Ni3+ ion parallels with the order of catalytic activities for CO oxidation At x = 0.5 the John-Teller distortion of BO6 octahedra appears, the max. value, as was expected from the results of axial ratio c/a.

Key words: CRYSTAL STRUCTURE, X-RAY DIFFRACTION ANALYSIS, STRUCTURE AND PROPERTY CORRELATION, LANTHANUM OXIDE, DOUBLE OXIDE, STRONTIUM OXIDE, CATALYTIC ACTIVITY