Electrochemical sensors based on carbon paste electrodes modified with Zinc oxide (ZC) and Zinc Oxide-Copper-Benzene Tricarboxylic acid (ZBC) were fabricated for voltammetric estimation of toxic Cd (II) ions in the matrix. Both the electrodes operate by showing interaction with Cd(II) ions and producing an electrical signal proportional to its concentration. The synthesized materials (ZnO and ZnO-Cu-BTC) were characterized by FTIR, XRD, SEM, EDX, TGA and electrochemical characterization by ElS and CV scans. Mixing appropriate amounts of graphite powder, synthesized material (ZnO or ZnO-Cu-BTC) and paraffin oil generated a variety of modified carbon paste electrodes as working electrodes. The electrochemical surface area for ZBC (1.1845cm2) was found to be much greater than for ZC (0.686 cm2). The fabricated working electrodes were utilized to optimize Cd(II) determination parameters (effect of modifier amount, accumulation media, pH, deposition potential, deposition time, and cadmium concentration) with potentiostat workstation using differential pulse method. The results revealed that 15% (w/w) ZnO and 1% (w/w) ZnO-Cu-BTC modifier amount, using HCl as supporting electrolyte at pH 4, and − 1.2 V deposition potential with 60 s deposition time were found to be the optimized conditions for Cd(II) ions determination. The LOQ was calculated to be 0.104 mgL−1 and 0.016 mgL−1, while LOD was found to be 0.034 mgL−1 and 0.0053 mgL−1 using ZC and ZBC, respectively. The ZBC was found to be better than ZC for Cd(II) ions determination as ZBC showed lower LOQ and LOQ, larger surface area, and smaller electrode modifier amount as compared to ZC. [ABSTRACT FROM AUTHOR]