In the present study the irradiation damage behavior of Zr-1 wt.% Nb fuel cladding alloy was investigated using X-ray diffraction (XRD), positron annihilation lifetime spectroscopy (PALS), transmission electron microscopy (TEM) and nano-indentation. The samples were irradiated at two different fluences of 5 x 10¹⁶ p/cm² and 1 x 10¹⁸ p/cm²  using proton beam of 3.5 MeV energy at room temperature. SRIM calculation showed an inhomogeneous damage distribution as a function of proton penetration depth with maximum damage at a depth of 68 μm. XRD analysis revealed variation in the microstructural parameters of irradiated samples after proton irradiation. PALS showed formation of open volume defects in the irradiated samples and a clustering tendency of the same with irradiation. The formation of <a>– and <c>– type dislocation loops and needle-shaped precipitates upon irradiation was demonstrated by TEM. The depth dependent hardness of the irradiated samples evaluated from nanoindentation technique was found to follow the damage distribution predicted by SRIM simulation.