This work presents a study of the luminescence properties of Er 3+ when included into two different TiO 2 hosts: A polycrystalline and an amorphous host. The two host environments were produced by depositing two thin films with different Er 3+ concentration using radio-frequency magnetron sputtering. Structural analysis revealed the presence of the rutile and anatase phases in the polycrystalline film. Time-resolved and steadystate photoluminescence measurements evidenced the presence of two distinct local Er 3+ environments in the polycrystalline host. For the amorphous TiO 2 host, only one Er 3+ environment was observed, which differed from the two environments in the polycrystalline host. A method for extracting a fast and slow time-resolved emission spectrum from the two observed local environments in the polycrystalline host is also presented.