In this study a novel electrode was developed to simultaneous determination of serotonin (5-HT) and sertraline (ST) in the presence of uric acid based on a glassy carbon electrode modified by a composition of Fe3O4@MCM-48-SO3H and multi-wall carbon nanotubes (MWCNTs) (Fe3O4@MCM-48-SO3H/MWCNTs/GCE). The results showed that the modified electrode is a promising one for the simultaneous determination of 5-HT and ST in the presence of uric acid (UA) at optimized circumstances. Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) techniques were used to study behavior of the modified electrode. The DPV results showed a linear relationship between 5-HT concentration and the oxidation peak current in the concentration ranges from 0.05 μM to 100 μM with a detection limit of 0.015 μM. For ST, a linear relationship between the concentration and the oxidation peak current in the ranges from 0.1 μM to 85 μM was obtained. The corresponding detection limit for ST was 0.025 μM. The Fe3O4@MCM-48-SO3H/MWCNTs/GCE was used for determination of 5-HT and ST in real samples like human blood serum and urine with reasonable outcomes.