Self-regulating pressure source. The pressure source includes a chamber enclosing a chemical monopropellant. A moveable boss is attached to a deformable membrane sealing an air chamber, the moveable boss and air chamber being disposed within the chamber. A catalyst is disposed around the membrane so as to be covered by the boss in a retracted position so that the monopropellant is broken down by the catalyst to produce a gas. The gas pressure will increase within the chamber causing air in the air chamber to compress thereby to pull the boss into the retracted position to cover the catalyst thereby to regulate the pressure within the chamber. The self-regulating pressure source is particularly suited to power fluidic elastomeric actuators.