9994 Grotius is a main belt asteroid. It orbits the Sun once every 4.15 years.
Discovered on September 24, 1960 by C. J. van Houten and I. van Houten-Groeneveld on photographic plates made by T. Gehrels, it was given the provisional designation 4028 P-L. It was later renamed 9994 Grotius, to honour Hugo Grotius.