Timeline-based planners have been shown quite successful in addressing real world problems. Nevertheless they are considered as a niche technology in AI P&S research as an application synthesis with such techniques is still considered a sort of “black art”. Authors are currently developing a knowledge engineering tool around a timeline-based problem solving environment; in this framework we aim at integrating verification and validation methods. This work presents a verification process suitable for a timeline-based planner. It shows how a problem of flexible temporal plan verification can be cast as model-checking on timed game automata. Additionally it provides formal properties and checks the effectiveness of the proposed approach with a detailed experimental analysis.