The creep of polycrystalline Hg2X2 (where X = Cl, Br, J) under the terrestrial and space conditions is studied in the present experiment. The authors suppose that the creep of the Hg2X2 cylindrical sample can be studied by the help of the theory of micropolar (non-Newtonian) fluids. In accordance with this theory we obtain the flux of fluid through any cross-section as functions of the radius, viscosity coefficients, the gradient of pressure and the gravity acceleration. In this paper a comparison of the theoretical results for normal and zero- gravity conditions is given. It is shown that the annealing of materials having a broad region of plasticity under microgravity conditions can lead to great improvement in optical as well as mechanical qualities of the crystal. Technical aspects of the experiment are also described.