The high-temperature X-ray diffraction methods were used to study the kinetics of ordering in stoichiometric Ni3Al alloyed with a third element (V,Ti, W, Nb, Cr, Co, Fe). Upon isothermal holdings at 1100, 1150, and 1200 degrees C, a "superstructure contraction" of the crystal lattice was observed. The degrees of long-range order at room temperature were determined for these alloys. Alloying with Nb, Ti, W, and V favors the retention of the high degree of long-range order in the alloy, whereas Cr, Co, and Fe added in Ni3Al decrease its value.