In the present paper, graphitic carbon nitride (g-C3N4) was prepared using a conventional hydrothermal process. Several characterization methods were applied to analyze the resulting g-C3N4 sample, such as: X-ray diffraction (XRD), ultraviolet-visible (UV–Vis) spectrophotometry, attenuated total reflectance -Fourier-transform infrared (ATR-FTIR) spectroscopy and scanning electron microscopy (SEM) equipped with energy-dispersive X-ray spectroscopy (EDS). The pollutant selected to measure the g-C3N4 photocatalytic performance was methylene blue (MB). Using Response Surface Methodology (RSM), the pH solution effects, photocatalyst dose (mg/L), and irradiation period (min) were examined and adjusted. The optimal conditions, which included 1.3 g/L of g-C3N4 photocatalyst, solution pH = 10.83, and irradiation time = 119.3 min, resulted in a degradation efficiency of 86.58 %. The principal active species involved in photocatalytic degradation have been identified and a potential mechanism has also been provided. Additionally, the degradation kinetics were monitored and obtained to follow pseudo-second order kinetics. Display omitted •g-C3N4 was synthesized successfully using a conventional hydrothermal method and characterized by different techniques.•The synthesized photocatalyst was used for the photocatalytic degradation of the organic pollutant MB.•The photocatalytic process was accompanied by RSM to optimize the factors using BBD theory.•The main active species involved in photocatalytic degradation were identified; a potential mechanism was proposed.