Polyetheretherketone is a semi-crystalline, thermoplastic, polyaromatic ketone. There are disadvantages to the addition of inorganic fillers as reinforcement. Nanoparticles derived from Neem (Azadirachta indica) leaves are organic sources to use as reinforcement of polyetheretherketone. Hence, it was investigated to evaluate the surface hardness, stiffness, and modulus of elasticity of PEEK-Azadirachta indica reinforced polyetheretherketone at varying weight percentages. Materials and Method - This experiment is intended to evaluate the surface hardness for mechanical behavior at micro and nano levels. A total of 96 samples (N=12 for each group) where 48 samples underwent the nanoindentation test and the remaining 48 samples for the microhardness test. The unreinforced PEEK specimens and nanoparticle-reinforced specimens were prepared by injection molding. The tests were carried out using a Nano Hardness Tester which shows elastic and plastic values (hardness, indentation modulus, and elastic modulus) of the tested material. A digital microhardness tester was used to observe the indentation made by the indenter on the surface of the specimen to calculate the hardness value. Results - One-way ANOVA of control and experimental groups showed a p-value for nano hardness-NH (P=0.000), microhardness-MH (P=0.041), reduced elastic modulus-ER (P=0.000), and contact stiffness-S (P=0.000). Conclusion – The addition of 10%, 20%, and 30% Azadirachta indica leaves nanoparticles as a reinforcement material does improve the nano hardness. A minimal decrease in microhardness was noted among 10%, 20%, and 30% PEEK-Azadirachta indica leaves nanocomposite. 30% PEEK-Azadirachta indica leaves nanocomposite had the highest reduced elastic modulus and contact stiffness followed by 20% and 10% PEEK-Azadirachta indica leaves nanocomposite.