The main purpose of this paper is to present a conceptual model for the use of web 2.0 online technologies in order to develop and enhance students' critical thinking skills at higher education level. Wiki is chosen as the main focus in this paper. The model integrates Salmon's 5-stage model (Salmon, 2002) with Garrison's Community of Inquiry (Garrison, Anderson & Archer, 2000), and is grounded in empirical data from three case studies. This model can act as a theoretical foundation for module leaders and practitioners to design and implement web 2.0 technologies to enhance students' critical thinking skills. The aim of the research was achieved by generating a 4-stage Online Presence (4-SOP) model. The 4-SOP model consists of four stages and three online presences to provide a step-by-step guide for module leaders and practitioners to introduce web 2.0 online technologies to students. This model can be applied to other web 2.0 online technologies tools rather than just focusing on wiki. The paper makes a contribution to the current state of the use of web 2.0 technologies especially in module design and delivery.