Abstract : We introduce a first-order extension of dynamic logic (FO-DL), suitable to represent and reason about the behaviour of Data-aware Systems (DaS), which are systems whose data content is explicitly exhibited in their description. We illustrate the expressivity of the formal framework by modelling English auctions as DaS and by specifying relevant properties in FO-DL. Most importantly, we develop an abstraction-based verification procedure, thus proving that the model checking problem for DaS against FO-DL is decidable, provided some mild assumptions on the interpretation domain.