Dielectric elastomer based prototype fiber actuators have been developed based on the concept of cylindrical dielectric elastomer actuators (DEAs). The prototype fiber actuators have been built using commercially available dielectric elastomer tubes, having wall thickness in the range of 100-200 microns, and applying appropriate compliant electrodes to inner and outer wall of these tubes. Actuation behavior of prototype fiber actuators has been studied under different boundary conditions and as a function of applied electric field. Actuation behavior constitutes axial and radial actuation strains as well as blocking forces produced in the prototype upon actuation. Different boundary conditions were achieved by applying different prestrains on the dielectric elastomer tubes. Two types of prestrains, uniaxial and uniform, at different levels were applied. Uniaxially prestrained prototypes were fabricated by prestraining the dielectric elastomer tubes along the axial direction. Two dielectric elastomers, silicone and polyurethane, with compliant polymer based inner and outer electrodes were used for fabrication. Uniformly prestrained prototypes were fabricated by inflating the dielectric elastomer tubes with an inflation medium. To keep the actuator design simple, inner electrode was used as the inflation medium. A strong electrolyte was used as the inner electrode whereas a polymer based electrode was used as the outer electrode. An experimental set-up was designed to conduct the actuation experiments and evaluate the actuation behavior of prototype fiber actuators. Actuation strains were measured using image analysis techniques and actuation blocking forces were measured using a load cell coupled to the prototype fiber actuator. A parabolic relationship was observed between applied electric field and axial actuation strains, radial actuation strains and actuation blocking force for the developed prototypes. Upon actuation of the uniaxially prestrained prototypes it was observed that axial strains and actuation blocking force decreased with the increase in uniaxial prestrain levels, and radial strains increased with the increase in uniaxial prestrain levels. Also, silicone based uniaxially prestrained prototype fiber actuators showed much higher actuation strains than the polyurethane based. In uniformly prestrained prototypes, axial actuation strains, radial actuation strains and actuation blocking force, all three, showed a decrease with increase in inflation pressure. To characterize the tubular actuators for their utility and to validate the experimental technique used in this study the prototype fiber actuators were tested for any hysteresis in their actuation behavior. No hysteresis was observed in the actuation behavior of both silicone and polyurethane based prototype fiber actuators.