The objective of this dissertation is to propose and apply a conceptual model for monitoring and evaluating research, development, and innovation (RDandI) projects of new complex products and systems (CoPS), using a methodological approach that integrates the Technology Readiness Level (TRL) scale with the Stage-Gate tool and employs two multicriteria decision support methods. The methodology comprises: (i) bibliographic and documentary research on the central themes of the research; (ii) development of the conceptual model for monitoring and evaluation RD(and)I projects of CoPS for the defense area, based on the Stage-Gate tool and the TRL scale; (iii) use of the Analytic Hierarchy Process (AHP) method in two moments, the first to define the weights of the criteria for validation of the quality of performance indicators related to RD(and)I projects; and the second to assign weights to the evaluation criteria for the mentioned projects at decision gates; (iv) use of the TOPSIS method to validate the quality of the performance indicators; and (v) application of the proposed model, focusing on an RD(and)I project underway at the Army Technological Center (CTEx), aiming to show its potential for replicability to other RD(and)I projects of CoPS at that Center. The main result is an innovative model for monitoring and evaluating RD(and)I projects of CoPS for the defense area, which can be applied at CTEx and other Science and Technology Institutions seeking excellence in innovation management, particularly when facing the challenges of CoPS development. The results of the empirical study conducted in this organizational context showed that it is possible to use the Stage-Gate tool and the TRL scale in an integrated and effective manner to monitor and evaluate RD(and)I projects of CoPS for the defense area throughout their development.