He has the ability to shoot lava from his head. His costume seemingly is a red jumpsuit and a volcano hat which spurts out lava. In "The Bad Guy Club for Villains," there's another superhero that's possibly the same person as Captain Magma, but is called "Professor Magma" and does not speak clearly, as he only makes gargle sounds.
Magma Spout; Lava will come out of his head if angered. Magma is triggered by the code word, "Krakatoa!!!"