Display omitted •Microextraction using DLLME was optimized by factorial design and Doehlert matrix.•Satisfactory recovery values were obtained in surface water samples.•The optimized method provided limits of detection between 0.55 and 0.85 μg L-1.•The developed methodology was applied for the analysis of metals in natural and drinking water samples. In this work, a dispersive liquid–liquid microextraction method combined with inductively coupled plasma optical emission spectrometry was developed to extract and pre-concentrate the trace metals cadmium and lead. Variables such as extracting solvent, dispersive solvent and chelating agent were studied using a univariate design. On the other hand, parameters such as pH, volume of the extracting solvent, volume of the dispersive solvent and concentration of the chelating agent were optimized using a factorial design 24. Doehlert design was used to improve the conditions established in the factorial design. The optimized method consisted of chelating agent concentration of 0.05 % (w/v), 8000 µL of dispersive solvent (ethanol), 600 µL of extracting solvent (chlorobenzene) and a pH of 7.0. Using these conditions, it was obtained a limit of detection of 0.85 and 0.55 µg L-1, enrichment factors of 13.4 and 10 and relative standard deviation of 0.8 and 3.7 % (5 µg L-1, n = 3) for the metals Cd and Pb, respectively. The developed methodology was applied for the analysis of cadmium and lead in natural and drinking water samples.