  The effect of annealing in high pressure oxygen atmosphere on superconducting
transition temperatures for ceramic samples of magnetic superconductor europium
based 1222 ruthenocuprate was studied. It was shown that the properties of the
samples are consistent with the behavior of granular superconducting system. As
a result of oxygen saturation the superconducting transition temperatures
become higher. Particularly, the shift of superconducting transition
temperature for the intergranular medium is 9.2 K and for the matter within the
granules 6.8 K. This difference is supposed due to the mechanism of oxygen
diffusion along the grain boundaries. In the temperature range between 135 K
and 350 K the behavior of resistance obeyed the Mott law of variable range
hopping for three dimensional case.
