Summary To improve the monitoring of methanotrophic activity, a competitive reverse transcription‐polymerase chain reaction (RT‐PCR) methodology was developed. Homologous internal RNA standards were created for mmoX and pmoA , genes encoding polypeptides of sMMO and pMMO, respectively. Using specific primer sets, expression of sMMO and pMMO could be quantified by means of competitive RT‐PCR and capillary electrophoresis with u...