Previous articles have described different aspects related to experimental set-ups, measurement and characterization techniques that can be applied to study heterogeneous photocatalysts . Particular attention has been paid to efficiency definitions in photocatalysis and photocatalyst activity metrics . Multiple photoreactor designs have been described, including batch and continuous reactors . However, most reactor configurations are quite complex (in case of microreactors) or require large volumes of photocatalyst dispersions (e.g. batch photoreactors). Furthermore, product analysis typically requires on-line gas chromatography, which is both costly and maintenance intensive. Therefore, there remains the need for simple testing protocols, which also enable control of all relevant reaction parameters and provide detailed insight into product formation.