Power of partners in supply chain is an essential concept in collaboration, which can influence the decisions and behaviours of the focal company. Therefore, any company has to have a good understanding on the power of partners in order to determine the possible opportunities or threats in a potential collaboration. In this paper we present a product-oriented power taxonomy obtained from the analyses on two classes of power factors: the partner-independent power factors and the partner-dependent power ones. The former are related to the product and market while the latter are intrinsic ability factors of partner such as reputation, knowledge and performance. Then we analyse the different aspects of each type of power and corresponding determinants. Furthermore, we propose a method to assess those determinants.