As more and more travelers wish to create their personalised trip itineraries, the provision of geographical information and services on travel websites is an unavoidable necessity. The evolution of geoportals, geocollaborative portals and web 2.0 present numerous opportunities and services for making the trip planning process less complex and time consuming, more efficient and more social and collaborative for travelers and their travel companions. This paper aimed at exploring the use and impact of geocollaborative portals on the success of collaborative trip planning processes. To that end, the literature was reviewed for analyzing the functionality of geoportals and geocollaborative portals and demonstrating how these can support and facilitate the collaborative decision making processes for trip planning purposes. A framework for measuring the impacts of geoportals’ use on travellers’ collaborative decision making processes was developed and tested by collecting primary data through an experimental study based on students’ perceptions using Yahoo! Trip Planner for planning a group trip. The paper provides useful practical guidelines for designing the functionality of geoportals and/or geocollaborative portals for trip planning purposes.