<p>A novel electrochemical phosphate sensor was developed based on a composite of CoMoO₄ nanostructures and ammonium molybdate tetrahydrate (AMT) deposited on the polyester conductive substrate (PCS). The CoMoO₄ nanostructures were synthesized using a simple hydrothermal method, followed by calcination. Raman analysis confirmed various stretching vibration modes of cobalt molybdate, with a sharp, intense peak at 944&#xa0;cm⁻¹ arising due to the symmetric stretching vibration mode of Mo–O. XRD analyses confirmed the formation of a monoclinic crystal system and highly pure CoMoO₄ with a C2/m space group. SEM analysis revealed rod-shaped morphologies of CoMoO₄. The PCS/AMT/CoMoO₄ electrodes exhibited remarkable electrochemical performance, with ammonium molybdate enhancing the Mo reduction peak response. This enhancement improved the sensor’s sensitivity for phosphate detection, as confirmed by cyclic voltammetry (CV) studies. The redox activity of the Co²⁺/Co³⁺ and Mo(VI)/Mo(V) couples contributed significantly to the enhanced electron transfer and redox reactions as observed in the sensing material. Hence, this sensor exhibited high selectivity and sensitivity, leveraging the catalytic properties of binary transition metal oxides. The CV responses of the sensor showed a clear correlation between Mo(VI) concentration and electrochemical activity, with improved performance compared to bare electrodes. The sensor exhibited a high sensitivity of (− 107.62 ± 10.94) (μA/μM)/cm² in the low concentration range (1–10&#xa0;μM), enabling trace-level detection, while maintaining a sensitivity of (− 3.688 ± 0.310) (μA/μM)/cm² for higher concentrations (10–320&#xa0;μM), ensuring stable response over a wide range. These findings highlight the potential of the AMT/CoMoO₄ nanomaterial as a highly sensitive and cost-effective electrode for phosphate monitoring, making it a promising candidate for environmental and analytical applications requiring precise quantification of phosphate levels.</p> Graphical abstract <p></p>