This work describes the development of a novel biofilm reactor-photoelectrocatalytic chemical oxygen demand (BFR-PeCOD) analytical system for rapid online determination of biodegradable organic matters (BOMs). A novel air bubble sample delivery approach was developed to dramatically enhance the BFR's biodegradation efficiency and extend analytical linear range. Because the air bubble sample delivery invalidates the BOD quantification via the determination of oxygen consumption using dissolved oxygen probe, the PeCOD technique was innovatively utilized to resolve the BOD quantification issue under air bubble sample delivery conditions. The BFR was employed to effectively and efficiently biodegrade organic pollutants under oxygen-rich environment provided by the air bubbles. The BOD quantification was achieved by measuring the COD change (Δ[COD]) of the original sample and the effluent from BFR using PeCOD technique. The measured Δ[COD] was found to be directly proportional to the BOD5 values of the original sample with a slope independent of types and concentrations of organics. The slope was used to convert Δ[COD] to BOD5. The demonstrated analytical performance by BFR-PeCOD system surpasses all reported systems in many aspects. It has demonstrated ability to near real-time, online determining the organic pollution levels of wide range wastewaters without the need for dilution and ongoing calibration. The system possesses the widest analytical liner range (up to 800 mg O2 L(-1)) for BOD analysis, superior long-term stability, high accuracy, reliability, and simplicity. It is an environmentally friendly analytical system that consumes little reagent and requires minimal operational maintenance.