The complexity of modeling mobile groupware systems is well known. The mobility of the collaborators, the diverse technologies available to support them and the continuous change in the collaboration scenarios bring new challenges to the design of these applications. Currently there are few languages explicitly designed to model these groupware systems. This paper presents the Mobile Collaboration Modeling language, a graphical language to represent loosely coupled mobile collaborative work This language may be used to communicate work practices, determine user requirements and design a groupware application that accurately supports collaborative mobile work. This article presents a case study illustrating the suitability of the proposal.