  We present extremal stationary solutions that generalize the
Israel-Wilson-Perjes class for the d+3-dimensional low-energy limit of
heterotic string theory with n >= d+1 U(1) gauge fields compactified on a
d-torus. A rotating axisymmetric dyonic solution is obtained using the matrix
Ernst potential formulation and expressed in terms of a single d+1 X d+1-matrix
harmonic function. By studying the asymptotic behaviour of the field
configurations we define the physical charges of the field system. The
extremality condition makes the charges to saturate the
Bogomol'nyi-Prasad-Sommerfield (BPS) bound. The gyromagnetic ratios of the
corresponding field configurations appear to have arbitrary values. A subclass
of rotating dyonic black hole-type solutions arises when the NUT charges are
set to zero. In the particular case d=1, n=6, which correspond to N=4, D=4
supergravity, the found dyon reproduces the supersymmetric dyonic solution
constructed by Bergshoeff et al.
