Efficient generation of THz pulses with high energy was demonstrated by optical rectification of 785-fs laser pulses in lithium niobate using tilted-pulse-front pumping. The enhancement of conversion efficiency by a factor of 2.4 to 2.7 was demonstrated up to 186 μJ THz energy by cryogenic cooling of the generating crystal and using up to 18.5 mJ/cm2 pump fluence. Generation of THz pulses with more than 0.4 mJ energy and 0.77% efficiency was demonstrated even at room temperature by increasing the pump fluence to 186 mJ/cm2. The spectral peak is at about 0.2 THz, suitable for charged-particle manipulation.