[en] The results of studying the diffusion of Cr impurity in GaAs according to electrical measurements are reported. Dependences of the diffusion coefficient and limiting solubility of electrically active Cr atoms in GaAs on temperature (at fixed pressures of As vapors) and on the pressure of As vapors (at fixed temperatures) are determined. The dependence of the Cr diffusion coefficient in GaAs on the ratio between the volume of the sample under study to the volume of the cell in the case of pronounced deviation from the crystal's stoichiometry towards Ga excess is established. The obtained experimental data are analyzed on the basis of concepts concerning the dissociative mechanism of migration of Cr atoms in the GaAs crystal lattice; according to this mechanism, the diffusion coefficient depends heavily on the concentration of Ga vacancies