Positron lifetime measurements using a Pulsed Low Energy Positron System (PLEPS) were applied to the investigation of defects in hydrogen implanted and subsequently thermally treated copper alloys which are designated for the use in the International T'hermonuclear Experimental Reactor (ITER). PLEPS results showed that the changes in the microstructure of selected copper-alloys (CuCrZr, CuAl25) depend strongly on the preparing technology of alloys and on the implantation dose. The full recovery of the structure after isochronal annealing in vacuum in a region of 100-600 degreesC was observed in all implanted specimens at a level of about 450 C. With the PLEPS technique, for the first time, depth profiling of the near-surface region (20-500 nm) of hydrogen implanted copper alloys was performed and compared with the transmission electron microscopy (TEM) studies.