In this study, we investigated the effect of modified material on screen-printed carbon electrode (SPCE) for detection of oxalic acid. The SPCE was modified with (1) carbon conductive ink and (2) combination of carbon conductive ink and nickel nanoparticles (Ni-NPs). Modification process of (1) was conducted using drop-cast method by adding a mix of carbon conductive ink and nickel nanoparticles (1:1) on the surface of SPCE. Modified SPCE was then dried and stored in desiccator. Performance test of SPCE with and without modification was carried out using cyclic voltammetry (CV) method. The CV scan was done at the range of-0.5 to 1.5 V with scan rate of 100 mV/s in 20 mM oxalic acid solution. The result showed that carbon conductive ink and nickel nanoparticles mix (1:1) modified SPCE could be used to detect oxalic acid on potential 1.2 V.