42 Leonis Minoris (42 LMi) is a solitary, bluish-white hued star located in the northern constellation Leo Minor. It has a visual apparent magnitude of 5.35, allowing it to be faintly seen with the naked eye. Parallax measurements place it at a distance of 412 light years. The object has a heliocentric radial velocity of, indicating that it is drifting away from the Solar System.
42 LMi has a general stellar classification of B9 V, indicating that it is an ordinary B-type main-sequence star. However, Cowley et al. (1969) gave a slightly cooler class of A1 Vn, indicating that it is instead an A-type main-sequence star with 'nebulous' (broad) absorption lines due to rapid rotation. Nevertheless, it has 2.77 times the mass of the Sun and a radius of . It radiates at 107 times the luminosity of the Sun from its photosphere at an effective temperature of . Its high luminosity and slightly enlarged diameter suggests that the object might be evolved. Like most hot stars, 42 LMi spins rapidly with a projected rotational velocity of .
There are two optical companions located near this star. BD+31°2181 is a 7th magnitude K2 giant star separated away along a position angle of . An 8th magnitude companion has been detected at a distance of over along a position angle of . Both have no relation to 42 LMi and is just moving with it by coincidence.
An X-ray emission with a luminosity of has been detected around the object. A-type stars are not expected to emmit X-rays, so it must be coming from an unseen companion.