The method of time-discretization is investigated in order to approxim
ate finite horizon cost functions for continuous-time stochastic contr
ol problems. The approximation method is based on approximating time-d
ifferential equations by one-step difference methods. In this paper ge
neral approximation results will be developed. An approximation lemma
is presented. This lemma enables us to conclude orders of converge, wh
ich makes the method of computational interest. Also unbounded cost fu
nctions are allowed. We concentrate on approximations induced by discr
ete-time controlled Markov processes. The approximation can in princip
le be computed recursively by using discrete-time dynamic programming.
In a subsequent second paper two applications will be studied in deta
il.