Humidity sensing characteristics of thick-film sensors based on α-Fe2O3 nanoparticles synthesized by hydrothermal method have been reported. The as-synthesized α-Fe2O3 nanoparticles were characterized by using XRD, Raman spectroscopy, TEM and HRTEM. Our TEM result depicts that the size of α-Fe2O3 nanoparticles were in the range of 20–30 nm with highly crystalline nature. For humidity sensing experiment, the sensitivity of our α-Fe2O3 nanoparticles-based sensor device was found to be ∼99% and the fastest response times were noted, which indicate that the α-Fe2O3 nanoparticle-based humidity sensor device has more future prospects and demand. The humidity sensing properties of α-Fe2O3 nanoparticles seem to be associated to the sorption sites for the water molecules at the nanoparticles interfaces.