Hammatoceras is a genus of ammonites belonging to the family Hammatoceratidae which lived during the Toarcian stage of the Early/Lower Jurassic between about 184 and 175 million year ago.

[1] Hammatoceras is included in the subfamily Hammatoceratinae, which in the outdated 1957 Treatise on Invertebrate Paleontology was part of the Hammatoceratidae, but of the Phymatoceratidae in D.T.

The superfamily Hammatoceratoidea in which the Hammatocaratidae and related families are currently placed is abandoned in favor of the older, equivalent, Hildoceratoidea.

Fossil shells within this genus have been found in Canada, France, Germany, Hungary, Indonesia, Italy, Spain, Tunisia and the United Kingdom.

Ribs arise from tubercles on the umbilical shoulder, the inner, dorso-lateral margin of the whorls, and bifurcate on the flanks, stopping at the ventral keel.