The computer code ODECS (Optimal Design of Engine Control Strategies) for the design of Spark Ignition engine control strategies is presented. This code has been developed starting from the author's activity in this field, availing of some original contributions about engine stochastic optimization and dynamical models.This code has a modular structure and is composed of a user interface for the definition, the execution and the analysis of different computations performed with 4 independent modules. These modules allow the following calculations: (i) definition of the engine mathematical model from steady-state experimental data; (ii) engine cycle test trajectory corresponding, to a vehicle transient simulation test such as ECE15 or FTP drive test schedule; (iii) evaluation of the optimal engine control maps with a steady-state approach. (iv) engine dynamic cycle simulation and optimization of static control maps and/or dynamic compensation strategies, taking into account dynamical effects due to the unsteady fluxes of air and fuel and the influences of combustion chamber wall thermal inertia on fuel consumption and emissions. Moreover, in the last two modules it is possible to account for errors generated by a non deterministic behaviour of sensors and actuators and the related influences on global engine performances. and compute robust strategies, less sensitive to stochastic effects.The computer tool ODECS. which is now being used by a major European automotive company, is particularly suitable for theoretical studies on the development of new engine control strategies for the reduction of air-fuel ratio excursions and of emission levels during transient manoeuvre. In an industrial environment the main applications are related to design analysis for the definition of both engine optimal control maps and control system strategies during transients.The submodels used have been validated through experimental analysis on dynamic test bench, and the results have been presented in previous papers. Further experimental activity is undergoing in order to fully validate the whole code.In the paper the four models are described together with significant results corresponding to the simulation and the calculation of optimal control strategies for dynamic transient tests.