Mobile nodes have been found useful for improving performance of network parameters such as coverage, data latency and load balancing in wireless sensor networks (WSNs). In spite of the benets which mobile nodes could oer when used in WSNs, they have been often stated as infeasible for use. As they are expensive compared to static nodes in terms of manufactur- ing and mobility cost. This paper evaluates the utility of mobile nodes for use in WSNs in comparison with static nodes. Novel geometric models to rep- resent the various functionalities for which mobile could be used have been proposed, they have been utilised for the techno-economic evaluation based on cost benet analysis. The models have been designed such that they give a generic representation of the functionalities, and enable a fair comparison between them. On the basis of the analysis it is concluded that apart from the functional utility, mobile nodes are economically benecial for use in WSNs.