The advances in authoring of interactive scores call for a thorough analysis of the written scores. A possible way to ensure correctness of an interactive score is through the use of formal techniques such as model checking. In this work, we present a visual model of the inter-media sequencer i-score and we propose a Timed Automata encoding to reason about the interactive scores written in this software. The verification of some properties of interactive scores is presented, along an evaluation of the performance of the model-checking process with uppaal.