The Maxwell-Chem-Simons gauge theory with charged scalar fields is analyzed at two-loop level. The effective potential for the scalar fields is derived in the closed form, and studied both analytically and numerically, It is shown that the U(1) symmetry is spontaneously broken in the massless scalar theory, Dimensional transmutation takes place in the Coleman-Weinberg limit in which the Maxwell term vanishes. We point out the subtlety in defining the pure Chem-Simons scalar electrodynamics and show that the Coleman-Weinberg limit must be taken after renormalization. Renormalization group analysis of the effective potential is also given at two loops. (C) 1997 Elsevier Science B.V.