Single crystal of high temperature phase of LiMnBO3 in the hexagonal (h) lattice has been grown by slow-cooling method with LiBO2 as flux. The transmission spectrum reveals that h-LiMnBO3 is highly transparent from 680 to 3000 nm and its absorption bands in the visible and ultraviolet regions are assigned to d-d transitions of Mn2+ ions. Second-harmonic generation (SHG) was measured with a fundamental light at 2090 nm using the Kurtz and Perry technique, which showed that its effective SHG coefficient was about half that of LiB3O5(LBO). AC impedance spectroscopy shows that along the crystallographic b axis the conductivity presumably due to Li ion migration is 1.1 x 10(-7) S cm(-1) at 394 degrees C and the activation energy E-a is 0.599 eV. Together with its chiral magnetic ground state, present study shows that h-LiMnBO3 is an interesting multifunctional material to possess also nonlinear optic and ionic conducting properties. (c) 2012 Elsevier Ltd. All rights reserved.