We have derived the dispersion relation for the lower-hybrid surface waves propagating perpendicularly to the magnetic field in the semi-bounded warm plasma. The mirror reflection boundary condition is adopted to obtain the surface mode of lower-hybrid plasma waves. The effects of magnetic-field strength and the finite ion temperature on the propagation of the lowerhybrid surface wave are investigated. The increase of ion temperature significantly increases the wave frequency, but an interesting hump of the group velocity appears in the region where the wavelength of the lower-hybrid surface wave is much larger than the electron Debye length. For cold ions, the surface wave is resonant near the lower-hybrid frequency as the wave number goes to infinity.
