Single crystal of high temperature phase of LiMnBO 3 in the hexagonal (h) lattice has been grown by slow-cooling method with LiBO 2 as flux. The transmission spectrum reveals that h-LiMnBO 3 is highly transparent from 680 to 3000nm and its absorption bands in the visible and ultraviolet regions are assigned to d–d transitions of Mn 2+ ions. Second-harmonic generation (SHG) was measured with a fundamental light at 2090nm using the Kurtz and Perry technique, which showed that its effective SHG coefficient was about half that of LiB 3 O 5 (LBO). AC impedance spectroscopy shows that along the crystallographic b axis the conductivity presumably due to Li ion migration is 1.1×10 −7 Scm −1 at 394°C and the activation energy E a is 0.599eV. Together with its chiral magnetic ground state, present study shows that h-LiMnBO 3 is an interesting multifunctional material to possess also nonlinear optic and ionic conducting properties.