This paper describes the development and electrochemical behaviour of a quick, easy, cheap and eco-friendly electroanalytical procedure for the direct analysis of dimethomorph fungicide (DIM) in natural water samples using a carbon-fibre microelectrode (CFM) coupled with square-wave voltammetry (SWV). The optimized experimental and voltammetric parameters employed were a 0.04molL⁻¹ Britton–Robinson buffer (pH 3.0), a pulse potential frequency of 70s⁻¹, a pulse amplitude of 30mV and a scan increment of 2mV. It was possible to observe a well-shaped oxidation peak at +1.25V (vs. Ag/AgCl/saturated Cl^–), which was related to a two-electron transfer in the quasi-reversible redox process affected by a strong adsorption of reactants and products on the electrode surface. Analytical parameters such as linearity range, correlation coefficients, detection and quantification limits were evaluated and compared to similar results obtained using gas chromatography coupled with mass spectrometry. However, by using SWV, no clean-up, extraction or pre-concentration procedures were necessary, making the electroanalytical procedure more feasible for analytical routine analysis.