This paper presents a supply chain collaboration service (SCCS) in SaaS paradigm to support inter-organization interaction between business partners. SaaS is very attractive to enterprises because it offers low cost and flexible on-demand IT solution. The paper presents an extensible service oriented architecture that can integrate business application as a service into SCCS. In order to improve the supply chain performance, it provides flexible support for information sharing between business partners. The SCCS prototype has been developed.