The formation of holographic gratings in nematic liquid crystals by laser beams in the telecommunications wavelength region around 1500 nm through a thermal mechanism has been demonstrated. The gratings have been observed in a four-wave mixing experiment with millisecond-long writing pulses in 5CB liquid crystal. The relatively low absorption of the crystal was compensated by the absorption in the coating of the experimental cell wall. Optimization of the liquid crystal temperature near the phase transition point allowed a diffraction efficiency of about 1 to be reached. Holographic liquid crystal devices can be used in all-optical switching, beam routing, automatic wavefront correction, phase conjugation, etc.