In an oxygen activity gradient, BaTiO3 ceramic generally relaxes twofold: a fast global relaxation in the oxygen sublattice and a sluggish ingrain relaxation in the cation sublattice(s), thus allowing one to simultaneously determine the two chemical diffusivities. [Yoo et al., J. Am. Ceram. Soc., 88, 617-623 (2005)]. Upon this ground, the chemical diffusivities have been measured, by a conductivity relaxation technique, on donor (La-Ba(center dot))-doped BaTiO3 ceramics with different Ba/Ti ratios, Ba1-xLaxTi1-x/O-4(3), Ba1-3x/2LaxTiO3 and Ba1-xLaxTiO3 all with x=0.01, against oxygen activity in the range of -15 <= log(Po-2/atm) <= 0 at 1200 degrees C. It has been found that the chemical diffusivities for the cation sublattice(s), and those for oxygen as well, are essentially the same irrespective of the Ba/Ti ratios. This fact indicates either that only either of Ba or Ti is mobile or both have about the same mobility. Circumstantial evidences support the latter. (C)2008 Elsevier B.V. All rights reserved.