Substitution of Ti at a Cu-site in the LnBa2Cu3-xTixO7+δ (Ln = Nd,Sm) system reveals single phase formation up to x = 0.3. The LnBa2Cu2TiO7+δ phases are predominantly single phases for Ln = La→Sm. Systematic studies of the LnBa2Cu3-xTixO7+δ (Ln = Nd,Sm) system reveal an O→T transition at x≈0.1. The oxygen content of the phases increases to ∼ 7.50 as x approaches 1.0. Electrical resistivity and AC magnetic susceptibility studies show that the superconducting transition temperature (Tc) decreases monotically as a function of Ti content. The initial rate of decrease of Tc is ∼ 15 K/at.% for Ln = Nd and ∼ 13 K/at.% for Ln = Sm. Tc vanished for x > 0.3 for the Nd-123 and x > 0.4 for the Sm-123 phases. The phases with x ≥ 0.5 show semiconducting behaviour. © 1993.