Measurement of extracellular enzymic activity in wetland soils can give an indication of the ecosystems biogeochemical processes, and rates of nutrient and carbon cycling. Analysis of these have allowed researchers to gain an understanding of the ecosystems’ microbial ecology and how it can be affected by environmental factors. Here we give a detailed description of the assays necessary to determine the activity of a suite of key hydrolase enzymes and phenol oxidases. These enzymes control the rates of decomposition and consequently the production of biogenic greenhouse gases. Knowing the processes responsible for the breakdown of organic matter is therefore essential if it becomes necessary to curb these emissions. Our protocols allow for cost effective analysis of a large number of samples and provide sufficient accuracy to determine differences between soil types. When coupled with contemporary microbial techniques these enzyme assays permit entire biochemical pathways to be determined, giving unparalleled knowledge on the processes involved in wetland ecosystems.