This paper considers the problem of designing heterogeneous multiprocessor embedded systems. The focus is on a step of the design flow: the definition of innovative metrics for the analysis of the system specification to statically identify the most suitable processing elements class for each system functionality. Experimental results are also included, to show the applicability and effectiveness of the proposed methodology. Keywords Heterogeneous Multiprocessor Embedded Systems, Metrics for Hw/Sw Partitioning, System-Level Design.