The present work aims the development of a biomimetic sensor for the detection of sodium diclofenac from a glassy carbon electrode modified with copper(II) 1,4,8,11,15,18,22,25-octabutoxy- 29H,31H-phthalocyanine complex and functionalized multi-walled carbon nanotubes (MWCNTCOOH). The proposed sensor was evaluated in batch system using 0.1 mol L-1 phosphate buffer solution at pH 7.5 as electrolyte support. A linear response was obtained in the range of 4.0 × 10-5 and 6.7 × 10-4 mol L -1, with the sensitivity of 6.1 × 105 (± 1.5 × 104) μA L mol-1 and detection limit of 1.3 × 10-5 mol L-1 using square wave voltammetry. The selectivity was studied by the sensor response in the presence of other drugs. The sensor was applied to pharmaceutical formulations and also to biological serum samples by recovery studies. When coupled to a flow injection system (FIA), the best results were obtained by applying the potential of 0.5 V vs. Ag|AgCl|KClsat, using an injected volume of the sample of 100 μL and a flow of 1.2 mL min-1. The linear response range in flow was between 5.0 × 10-5 and 5.0 × 10-3 mol L -1, with a sensitivity of 1.6 × 104 (± 3.0 × 102) μA L mol-1 and a relative standard deviation of 3.5%. © 2014 Sociedade Brasileira de Química.