Members of the Cryomonadida are single-celled organisms that are surrounded by a shell comprising layers of organic material. They possess two unequally long flagella, and a single nucleus with a distinct nucleolus. They have a laterally located cytostome, from which pseudopodia arise.
The order Cryomonadida was erected in 1993 for the genus Cryothecomonas. In 2005, Sina Adl et al. did not include the order in their classification, but placed the genus incertae sedis among the Cercozoa. It became clear, however, that other genera, and taxa known only from environmental DNA, belonged in this group, and so in 2008 Jan Pawlowski placed the Cryomonadida as part of the core Cercozoa.
The following genera are included: