The spontaneous electric polarization (SEP) in the multiferroic Ga2-xFexO3 (x = 1/2, 1, 3/2) systems is determined from their electronic structure using a first principles method and the modern theory of polarization. This is done by following carefully the SEP on a path connecting the polar and centrosymmetric structures. For the antiferromagnetic GaFeO3 system, the SEP is found to be-25.0 mu C/cm(2) which is 10 times larger than previous estimation given into the literature a few years ago. Similar SEP values are obtained for x = 1/2 and 3/2 where the system is highly magnetized. The homogeneous switching of this SEP through a centrosymmetric structure is discussed in terms of the total energy barrier and it is exhibited that such a process is particularly difficult to achieve in relation with the tetrahedral environment of half of the Ga atoms into the polar structure. (C) 2012 Elsevier B.V. All rights reserved.