Room temperature irradiation of InSb(111) by 60keV Ar+-ions at normal (0°) and oblique (60°) angles of incidence led to the formation of nanoporous structure in the high fluence regime of 1×1017 to 3×1018 ions cm-2. While a porous layer comprising of a network of interconnected nanofibers was generated by normal ion incidence, evolution of plate-like structures was observed for obliquely incident ions. Systematic studies of composition and structure using energy dispersive x-ray spectroscopy, Raman spectroscopy, x-ray photoelectron spectroscopy, Raman mapping, grazing incidence x-ray diffraction, and cross-sectional transmission electron microscopy revealed a high degree of oxidation of the ion-induced microstructures with the presence of In2O3 and Sb2O3 phases and presence of nanocrystallites within the nanoporous structures. The observed structural evolution was understood in terms of processes driven by ion-induced defect accumulation within InSb. © 2014 AIP Publishing LLC.