This article concerns a class of two-time-scale single-input single-ou
tput nonlinear systems. For such systems, combination of singular pert
urbation and geometric methods is employed to synthesize well-conditio
ned static state feedback laws that induce a well-characterized input-
output behaviour and guarantee stability of the closed-loop system. Th
e developed control laws are applied to two nonlinear chemical process
es with time-scale multiplicity and their performance is evaluated thr
ough simulations.