We report the synthesis of YBa2Cu3O7-delta (Y-123 phase)-single crystals, through a different path to the traditional one -which involves Y2BaCuO5 (Y-211 phase) as a precursor -. In our case, at 970 degrees C a Pt compound appears: Y2Ba3Cu2PtO10 which dissolves in the melt when heated at 1100 degrees C allowing the growth of Y-123 phase. Large single crystals of Y-123 phase obtained through the route developed in this study showed good superconducting properties with a transition temperature onset at about 85 K; this transition temperature is shifted towards higher temperatures through oxygenation processes that are favoured by their dimensions.