Accelerated water and moisture degradation of YBa2Cu3O7(YBCO)‐silver nonrandom composites is studied. Oxygen evolution for these composites immersed in water at 65 °C was compared with that for regular YBCO ceramic material prepared under similar sintering conditions. Time evolution of the decay of crystalline structure was followed by x‐ray diffraction for the composite material and for the regular YBCO ceramic. We find that the nonrandom Ag‐YBCO composite exhibits high chemical and structural stability in the presence of water; this advantageous property is probably due to the encapsulation of the YBCO grains with silver in this composite material.