Orthorhombic YMnO3 (o-YMnO3) is on the verge of the commensurate E-type phase adjacent to the bc cycloidal spin phase in the multiferroic orthorhombic RMnO3. Both polycrystalline bulk and thin-film samples of o-YMnO3 show a signature of the phase coexistence of these phases. Previous neutron diffraction studies suggested that the magnetic ground state of o-YMnO3 has an incommensurate spin arrangement, which is not compatible with the E-type phase. We manage to synthetize single crystal of o-YMnO3 by high pressure synthesis. We propose to investigate the magnetic ground state of o-YMnO3 and the ferroelectric distortion using the single crystal diffractometer D9 and D10.