An accurate and fast quantification of dissolved organic carbon (DOC) is essential for the characterization of the water quality in all kinds of water and for the evaluation of the efficiency of treatment processes. The conventional DOC determination method consists of on-site sampling and subsequent analysis in a stationary laboratory. However, this method is difficult to operate in cases where no or only poorly equipped laboratories are available in the vicinity of the sampling points. The objective of the present study is to investigate and to optimize a newly developed DOC determination method as a core element of a portable device. In addition, a first validation of a laboratory setup of this DOC analyzer is conducted. This analytical method is based on a miniaturized electrolysis decomposition cell equipped with a boron-doped diamond electrode (BDD). Within this study, the decomposition of different organic compounds (e. g. aromatic, aliphatic, and heterocyclic compounds) under galvanostatic conditions in an undivided electrolytic cell is systematically investigated. Experimental data, including studies on the influence of process and hydrochemical parameters, demonstrate the general suitability of the technical approach for practical on-site applications. The key features are: no need for extern ultra-pure gases, catalysts or burning technology, a low level of maintenance, and an analyzing time per sample below 7 min.