The R&D processes generate knowledge and enhance innovation activity. Knowledge and ideas developed by one agent may spill over to and can be used for economic and acquired by other agents. The results of these processes are known as the R&D spillover effects. Factors, that have influence on innovation diffusion, and determine the place of the R&D spillovers in knowledge-based economy have been investigated in the article. The definition and types of knowledge have been examined. The relationship between the R&D cooperation, different types of knowledge, knowledge spillovers and innovation have been traced. The main objectives of the paper are to consider the concept of the R&D spillovers and connection between different types of knowledge and the R&D spillover effects. Systematic comparative analysis, synthesis and generalization of the scientific literature have been carried out in order to create the theoretical background of the research of the R&D spillovers and innovation. The qualitative research methods have been employed to investigate relationship between the R&D spillovers and different types of knowledge. The R&D positive effect of spillovers on innovation activity, promotion of cooperation between different agents (individuals, business entities, organizations, and countries), spreadability and access to knowledge on nonprofit basis and enhancement of innovation diffusion have been identified.