An investigation of the micromachining of trenches in lithium niobate (LiNbO3) using direct imaged 248 nm KrF excimer laser ablation is presented. Trenches 20 µm wide and 0.5¿7.5 µm deep have been produced. These trenches are assessed and are deemed suitable for the machining of integrated electro-optic structures. Based on the characterized ablation conditions, trenches of high quality have been successfully fabricated on an X-cut optical modulator which is potentially important for the realization of efficient broadband optical intensity modulators.