Nanopattern formation on CoxS1-x (0 < x < 1) surfaces has been studied under a range of low energy Ar+ ion bombardment at oblique incidence and also at varying ion fluences. Our study shows a clear morphological change for the nanostructures depending upon the incident beam energies and binary mixture stoichiometries. From an initial smoothening regime, well-ordered nanoscale ripples form at sub-keV energies at ion fluences similar to 10(-1)(8) ions cm(-2) . These ripples further transform into micrometer-sized ellipsoidal structures upon increasing the ion energy from 500 eV to 1200 eV. The wavelengths of the nanostructures increase with ion fluence obeying a power law behaviour f(0.123), where f is the fluence. For higher values of Co content, the rippled morphology is gradually replaced by bug-like hierarchical structures.