Abstract The off-stoichiometric Ni50Mn34In16 intermetalic Heusler nanoparticles have been prepared by laser ablation in distilled water from the target alloy using femtosecond laser system. The properties of the particles were characterized by electron microscopy and magnetometer techniques. The particle mean size of 28nm was estimated by using the scanning electron microscopy images. However, the transmission electron microscopy results revealed that spherical cluster-like particles have been also produced. The magnetic field-induced structural transition was found in the particles with a starting temperature of around 250K.