3D-ensembles of gold nanowires electrodes (3D-NEEs) are produced by electroless gold deposition in track-etched polycarbonate (PC) membranes, followed by partial etching (plama or chemical) of the polymeric membrane. These electrodes are applied to the anodic stripping voltammetric determination of inorganic As. The controlled etching of the PC template increased the gold surface area, widening the linear range of the analytical response with respect to ensembles of gold nanodisk electrodes (2D-NEEs). 3D-NEEs prepared using a chemical etching time of 10 s allows the anodic stripping determination of As(III) with a detection limit of 0.08 μg/L and a linear range extended up to 20 μg/L. The speciation of inorganic As (As(III) and (As(V)) in river water is possible by difference between As(III) and total inorganic As, determined after reduction of As(V) with cysteine. The proposed method is successfully validated by comparison with lCP-MS determination.