A brief review of the present knowledge of hydrophilic poly(2-hydroxyethyl methacrylate) sponges is followed by an experimental study confirming that phase separation and subsequent chemical gelation (due to crosslinking) have crucial roles in the formation of sponges. Time onsets of the two processes were estimated by indirect methods, spectrophotometry and rheometry, respectively. Environmental scanning electron microscopy suggested that the mechanical properties of sponges are significantly influenced by the porous morphology.