Riboswitches are structural RNA elements mostly found within the untranslated regions of bacterial messenger RNAs (mRNAs) and play an important role in regulating gene expression at the level of transcription or translation. Here we use techniques of cryo-electron and single molecule microscopy in order to investigate the regulation of transcription termination mediated by the fluoride-sensing riboswitch. We expect to identify key interactions between the RNA polymerase and the riboswitch specifically within the active site and the RNA exit channel that will help to illuminate the mechanism of transcription termination.