Recently we have found multiferroic-like properties in an S=1/2 Cu2+ quantum-spin triangular-lattice compound CuOHCl. It showed geometric frustration and antiferromagnetic transition at TN = 11 K, but with an anomaly followed below 5 K. An extensive study on this new compound has suggested a multiferroic transition at 5 K. Therefore, establishing such a new triangular-lattice multiferroic system is of great current interest. Therefore, we propose muSR experiments on single crystals. The single crystal muSR would enable us to uncover the the mechanism of the newly found multiferroicity in an interesting material system.