A carbon paste electrode, modified with 2, 2′-[1,7-hepthandiylbis(nitriloethylidyne)]-bis-hydroquinone and TiO2 nanoparticles, was used for the simultaneous determination of dopamine (DA), uric acid (UA), and l-cysteine. The study was carried out by using cyclic voltammetry, chronoamperometry, and square wave voltammetry (SWV) techniques. Some kinetic parameters such as the electron transfer coefficient (α) and heterogeneous rate constant (ks) were also determined for the DA oxidation. A dynamic range of 8.0–1400 μM, with the detection limit of 8.4 × 10−7 M for DA, was obtained using SWV (pH = 7.0). The prepared electrode was successfully applied for the determination of DA, UA, and l-cysteine in real samples.