Preparation of Sr-11 substituted delta-SryAg,0.75-2yV2O5 and its lithium insertion behaviour were investigated. Isostructural substitution is possible within gamma = 0.1. Lithium insertion proceeded in three steps, and in the first step lithium insertion occurs in the single phase, the limiting composition of which is controlled by the ratio of V-IV to V-V in the oxide. Reversibility in insertion/extraction cycle is improved by Sr-11 substitution.