The Italian fossil baleen whale Aulocetus sammarinensis Capellini, 1901, represents a new genus, Titanocetus. The holotype skull of Titanocetus sammarinensis has a long ascending process of the maxilla, a wide and flat rostrum, a triangular interorbital region of the frontal, an anteriorly extended apex of the zygomatic process of the squamosal, and an anteriorly rounded, concave supraoccipital. Features primitive for mysticetes include strong bulging of the squamosal and parietal into the temporal fossa, a lambdoidal crest posterior to the occipital condyles, and a marked intertemporal constriction involving the parietals. Archaeocete-like features are the round anterior process of the supraoccipital and nasals that are transversely constricted anteriorly. These and other features suggest that Titanocetus sammarinensis represents an early-diverging baleen-bearing mysticete probably related to Cetotherium-like taxa.