Résumé : Urban metabolism (UM) is a way of characterizing the flows of materials and energythrough and within cities. It is based on a comparison of cities to living organisms, which,like cities, require energy and matter flows to function and which generate waste duringthe mobilization of matter. Over the last 40 years, this approach has been applied innumerous case studies. Because of the data-intensive nature of a UM study, however, thismethodology still faces some challenges. One such challenge is that most UM studies onlypresent macroscopic results on either energy, water, or material flows at a particular pointin time. This snapshot of a particular flow does not allow the tracing back of the flow’sevolution caused by a city’s temporal dynamics. To better understand the temporal dynamicsof a UM, this article first presents the UM for Brussels Capital Region for 2010, includingenergy, water, material, and pollution flows. A temporal evaluation of these metabolic flows,as well as some urban characteristics starting from the seminal study of Duvigneaud andDenayer-De Smet in the early 1970s to 2010, is then carried out. This evolution showsthat Brussels electricity, natural gas, and water use increased by 160%, 400%, and 15%,respectively, over a period of 40 years, whereas population only increased by 1%. Theeffect of some urban characteristics on the UM is then briefly explored. Finally, this articlesuccinctly compares the evolution of Brussels’ UM with those of Paris, Vienna, Barcelona,and Hong Kong and concludes by describing further research pathways that enable a betterunderstanding of the complex functioniong of UM over time.