A study on the influence of titanium on the diffusion kinetics of erbium in lithium niobate is presented. An empirical linear relation between the diffusion coefficient of erbium and the initial film thickness of titanium was obtained from secondary ion mass spectrometry data. An improvement in the diffusion coefficient by a factor of two was measured for a 200-nm titanium film. Furthermore, the erbium and titanium codiffusion process not only enhances the diffusion of erbium, leading to smaller diffusion time, but also improves the device visibility for further fabrication procedures. This letter is envisioned to clarify in a quantitative way the process of simultaneous codiffusion of erbium and titanium ions into lithium niobate, which has been studied by several authors; nevertheless, no definitive conclusion can be found in the literature.