The half-metallic Heusler alloy Ni2MnIn is of high interest for use in spin electronics since at the Ni2MnIn/InAs interface a spin polarization of 100% is predicted. We prepare high-quality thin films of 20–60 nm thickness by co-evaporation and DC magnetron sputtering. Point-contact Andreev reflection spectroscopy yields a spin polarization of up to 54%. By spectral generalized magneto-optical ellipsometry, the dielectric and magneto-optical properties are determined and ferromagnetic behavior below the Curie temperature is proved.