Microcalicium is a genus of lichen-forming fungi in the order Pertusariales. It is the only genus in the monotypic family Microcaliciaceae. These taxa were circumscribed by the Finnish lichenologist Edvard August Vainio in 1927, with Microcalicium disseminatum assigned as the type species.
Species of Microcalicium have a mazaediate ascomata (an irregularly spherical fruiting body in which ascus walls break down to leave a dry, loose, amorphous, powdery, often dark, mass of spores together with disintegrating asci and paraphyses). Their asci are ellipsoid in shape and non-amyloid.
, Species Fungorum accepts the following five species in the genus Microcalicium: