In this paper we present \sc Troll, a formal object-oriented specification language thought for the conceptual modelling of distributed information systems. \sc Troll offers both textual and graphical notations. \sc Troll has been used in practice to model an industrial information system. We use a simplified extract of this case study to describe briefly the syntax and underlying semantics of the language. We also show a set of software tools that are being developed for supporting the modelling with \sc Troll. These tools include editors, checkers as well as an animator for validating \sc Troll specifications. We report on the experiences we gained by applying the language to the industrial project. Finally, a short description on further work is given.