Chemical oxygen demand (COD) is an important water quality parameter for estimating organic pollution. Conventional COD method has several drawbacks including lengthy assay time, complex procedure and requiring the use of highly toxic and expensive chemicals. Considerable efforts have been devoted to improve conventional COD methods. In this regard, the PeCODTM method has been the most noticeable technique. This method utilizes the superior oxidation power of UV illuminated nanostructured titanium dioxide (TiO2) to achieve organic degradation while simultaneously enabling quantification of the COD value by directly measuring the photocatalytic oxidation current/charge that originated from photocatalytic degradation of organics. The method is an absolute method that requires no calibration. It is an environmentally friendly method that requires/generates no toxic reagent. It is a simple and rapid method for sensitive and accurate COD determination. However, PeCODTM method needs to be improved in few aspects for more broad applications, especially for the field-based applications. These include the portability and high degradation efficiency for those oraganic compounds with difficulty to be oxidized. This study is therefore focused on improving the portability and applicability of PeCODTM method.