RNA can provide valuable insights into the variability of metabolic processes of prokaryotes in space and time. However, due to the uncertainties about the stability of RNA, its application for activity profiling of environmental samples is questionable, particularly when the RNA cannot be stabilized instantly after collecting the sample. Thus, we explored different factors affecting the decay rate of transcripts of three marine bacterial isolates using qPCR. Additionally, we determined the half-life time of the mRNA from distinct bacterial taxa as well as of functional genes by metatranscriptomics of a coastal environmental prokaryotic community.