The ordering kinetics of the L12 alloy (Co0.78Fe0.22)3V have been studied on annealing below the order-disorder transition temperature and starting from different initial conditions induced by different thermo-mechanical treatments. The results obtained are reported in two parts. In Part I, we have determined by means of dilatometric, resistometric and calorimetric analysis, the relevant temperatures and energies dissipated in the transformations, and how the rates are affected by the initial conditions and annealing temperatures. The variation of hardness and the long-range order parameter have also been measured. The results obtained suggest that the overall kinetics are dependent on the way in which ordering, recrystallization and recovery phenomena occur at different temperatures and on how they affect each other. © 1993 Chapman & Hall.