The viability of graphitic carbon nitride (g-C3N4) in photocatalytic discipline has been studied before but its extensive usage has been halted due to large band gap energy. Therefore, this study is to enhance the photodegradation efficiency of g-C3N4 by treating them with acid. The precursor of synthesizing the photocatalyst, melamine was treated with several acids to determine which acid treatment would yield the best antibiotic ciprofloxacin removal. The melamine was calcined at 550 °C for two hours to produce g-C3N4. The experiment outcome was that g-C3N4 treated with sulphuric acid have the highest performance with 71.3 of ciprofloxacin removal after 120 minutes under visible light irradiation. FESEM, BET, FTIR, and XRD analysis were also performed on the as-developed catalyst. As for overall result, it is found that the g-C3N4 treated with H2SO4 exhibited the best ciprofloxacin removal efficiency in comparison to the pristine g-C3N4 and g-C3N4 treated with HCl and HNO3. © Malaysian Journal of Microscopy (2020). All rights reserved.