For sustainable future eco-innovation will play a major role. Understanding the diffusion is critical, since the diffusion rate is slow and the path unclear. We present the conceptual methodology for eco-innovation diffusion. This methodology combines mixed and combined research methodology to improve the validity and reliability of results. As quantitative methods the survey is used, as qualitative the artificial neural networks and system dynamic is applied. With this article we aim to contribute to the applications of combined and mixed methods research in the field of eco-innovation diffusion. The application of the presented methodology can be extended for other problems.