Modern respirometry has evolved significantly over the past decade. This article reviews the application of XC and ER series respirometers developed by ECHO Instruments across diverse biodegradation scenarios. It highlights an advanced approach to biodegradation monitoring by coupling these automated respirometry systems with cavity ring-down spectroscopy (CRDS) isotope analysers. This approach enables monitoring of the isotopic composition (δ¹³C) of evolved CO₂ and allows differentiation between carbon originating from the test material and carbon derived from background organic matter. Isotope-resolved methods offer significant advantages for future research and the analysis of complex biodegradation systems.