Chitosan (CS) has been explored in various fields due to its specific properties. Modifications to the glucopyranoside ring of chitosan expand its applicability, improving its existing characteristics and enabling new applications. This study aimed to modify CS with maleic anhydride (MA) at two different temperatures (30°C and 60°C) to investigate the influence of reaction conditions on the properties of the resulting complex. The effect of maleic anhydride on chitosan has been studied using Infrared Spectroscopy (ATR-FTIR), Tensile tests and Contact Angle Measurements. The attachment of MA to the CS backbone has been confirmed by infrared spectroscopy. The mechanical properties and surface free energy values show considerable differences compared to those of pure CS. The results demonstrate that MA incorporation significantly alters the structure–property relationships of CS films. The Young's modulus values were higher, and the contact angle results indicate the improved hydrophilicity of the grafted samples. The physicochemical properties were significantly improved after the incorporation of MA, due to hydrogen bonds formed within the CS matrix. This work establishes a foundational understanding of the basic physicochemical properties of CS–MA complexes and demonstrates how these properties can be tailored through controlled modification toward developing advanced functional systems for biomedical applications such as wound dressing, tissue engineering scaffolds etc.