  Starting with the generalized potentials, currents, field tensors and
electromagnetic vector fields of dyons as the complex complex quantities with
real and imaginary counter parts as electric and magnetic constituents, we have
established the electromagnetic duality for various fields and equations of
motion associated with dyons in consistent way. It has been shown that the
manifestly covariant forms of generalized field equations and equation of
motion of dyons are invariant under duality transformations. Quaternionic
formulation for generalized fields of dyons are developed and corresponding
field equations are derived in compact and simpler manner. Supersymmetric gauge
theories are accordingly reviewed to discuss the behaviour of dualities
associated with BPS mass formula of dyons in terms of supersymmetric charges.
Consequently, the higher dimensional supersymmetric gauge theories for N=2 and
N=4 supersymmetries are analysed over the fields of complex and quaternions
respectively.
