No research explored intellectual capital about green innovation or environmental management. This study wanted to fill this research gap, and proposed a novel construct - green intellectual capital - to explore the positive relationship between green intellectual capital and competitive advantages of firms. The empirical results of this study showed that the three types of green intellectual capital - green human capital, green structural capital, and green relational capital - had positive effects on competitive advantages of firms. Moreover, this study found that green relational capital was the most common among these three types of green intellectual capital, and the three types of green intellectual capital of Medium & Small Enterprises (SMEs) were all significantly less than those of large enterprises in the information and electronics industry in Taiwan. In sum, companies investing many resources and efforts in green intellectual capital could not only meet the trends of strict international environmental regulations and popular environmental consciousness of consumers, but also eventually obtain corporate competitive advantages.