We have performed a comprehensive investigation of the growth parameter space for the MOVPE of a-plane ( 1 1 2 ¯ 0 ) InN on a-plane GaN buffer layers deposited on r-plane ( 1 1 ¯ 0 2 ) sapphire substrates. About 0.2 μ m thick a-plane InN epilayers were grown on 1 μ m thick a-plane GaN buffer layers in a close-coupled showerhead reactor. The growth parameters—substrate temperature, reactor pressure, V/III ratio—were systematically varied and their effect on structural, electrical, optical and morphological properties of a-plane InN films were studied. All a-plane InN epilayers show an anisotropy in the in-plane mosaicity. The ( 1 1 2 ¯ 0 ) ω -fwhm varies depending on the scattering vector being parallel to the c-direction or the m-direction. The magnitude and nature of this anisotropy is strongly influenced by the growth parameters. In general compared to c-plane InN, we observed a higher growth rate and a slightly higher optimum growth temperature for the a-plane InN epilayers. The optimum growth conditions are found at T=550 °C, P=500 Torr, V/III = 11,000, where the ω -fwhm for symmetric ( 1 1 2 ¯ 0 ) reflections are 0.83° and 1.04° along [0 0 0 1] and [ 1 1 ¯ 0 0 ] directions, respectively, and for the skew-symmetric ( 1 0 1 ¯ 1 ) plane is 1.47°. The optimized a-plane InN has a photoluminescence peak emission at 1750 nm (0.71 eV) at low temperature (11 K) and a mobility of 234 cm 2/V s, carrier concentration 1.4×10 19 cm −3 at room temperature.