It is well known that switching dc-dc converters show a wide range of nonlinear behaviours including bifurcation, sub-haraionics and chaos when they operate outside their design specifications. These nonlinear patterns force the converter to change its normal periodic behaviour to a random-like behaviour; a situation that must be avoided. In this thesis, the nonlinear dynamics of switching dc-dc converters are investigated. It is shown for the first time that the concept of the monodromy matrix (i.e. the state transition matrix for one switching cycle, including the state transition matrices during the switching slants) can be successfully applied to determine the stability of switching dc-dc power converters.