Traffic, accessibility, employment location conditions, economic aspects, land-use policies among others are some factors that influence the location decisions of office firms. As a multidimensional decision making process, elements for supporting real-estate managers and planners in such decisions are needed. The objective of this study is to develop a GIS-based tool to support firms seeking office accommodation within a given regional or national study area. The basis of the tool relies on a matching approach, in which a firmís characteristics (demand), environmental conditions and office spaces on offer (supply) are analyzed separately in a first step. Subsequently, a matching process between them is performed and, finally, a suitability score is obtained for every office space on offer by applying some value judgment (satisfaction, utility etc.) to the overall match. Focusing on location aspects, expert knowledge about location decisions of firms/organizations regarding office accommodation, acquired from a group of real-estate advisers and stored in decision tables, constitutes the core of the model. Apart from the delineation of location choice sets for a firm seeking a location, this design of the system supports two additional types of queries. First, the agent supports the more generic problem of determining the allocation between a set of firms, on the one hand, and a set of vacant locations, on the other. Second, the agent provides the facility of finding firms that meet the characteristics of a given location. Technically, this problem is equivalent to a problem of finding the delineation of location choice sets for a firm seeking a location. Both of them consist of a sorting procedure. As a GIS-based tool, the results can be visualized using GIS features such as thematic maps and overlay techniques, allowing several types of analyses.