A reversibly stretchable supercapacitor using buckled single-walled carbon nano-tube (SWNT) macrofilms as the electrodes is demonstrated. A controllable wavy geometry and an extremely high stretchability (up to 30%) is achieved utilizing poly (dimethylsiloxane) (PDMS) as an elastomeric substrate (see image). The stretchable supercapacitors exhibit very stable capacitance under cyclic stretching and releasing, with capacitance values comparable to that of a supercapacitor assembled with pristine SWNT films.