Abstract: An improved robotic contractile device having, besides general industrial and other-wages applicability for automation and other purposes, particularly attractive utility in and for prosthetic appliances and which is characterizable in being able to function in a way remarkably analogous to that of biological muscle is structurally made up of an expandable conduit which is contractible on fluid inflation with a plurality of longitudinally-directed filaments peripherally-secured thereabout that are connectable with an object to be moved or displaced as a result of the contractability experienced upon inflation of said conduit; there being associated means in the device for introducing and exhausting fluid under pressure to the interior of the said conduit in order to inflate same to effectuate its motive contraction action and deflate it to its normal rest condition of maximum or intermediate extension.