Single-crystalline InN nanorods were successfully grown on c-Al 2 O 3 , GaN, Si(111), and Si(100) substrates by non-catalytic, template-free hydride metal-organic vapour phase epitaxy (H-MOVPE). It was evaluated thermodynamically and confirmed experimentally that the domain of nanorod growth lies in the vicinity of the growth-etch transition. Stable gas phase oligomer formation is suggested as the nucleation mechanism for InN nanoparticle generation. Dislocation-free, high-quality InN nanorods with [00.1] growth axis were formed via an apparent solid-vapour growth mechanism. The nanorod diameter, density, and orientation were controlled by growth temperature, substrate selection, and HCl/TMIn and N/In inlet molar ratios. S Supplementary data are available from stacks.