The main purpose of the thesis is to develop a multicriteria decision methodology to support the group negotiation, based on the classic multicritera approaches technical and behaviour metaphors. Such a methodology combines the multicriteria approaches as tool, where the decision agents can use them to analyse, to compare, to select and to rank the non domain solutions, by their preferences and resources. Negotiation is a interactive decision process between two or more agents to research their preferences and needs agreement. The search of the consensus on the group is one important source to the framework and it is primordial the basis of the multicritera approaches technical and behaviour metaphors. These metaphors mix the computer and communication technologies and help, capacity and efficiency, the agents to use the multicriteria approaches. The vigour and value of the multicriteria group system is confirmed by two simulate cases (case 1 - Purchase a Flat; case 2 - The new VW Truck Assemble). They show the approach utility on group decision: the goals flow to high group preferences and homogenous levels; the criteria s increase their value and dynamics, they exchange themselves to decision and last group criteria s (independent, robust and better quantifies ones) to compound a total factor or an identical sum to the criteria properties; the non-domain solutions are compared each other in progression stages, first by the individual criteria properties, after by the group criteria s and finally by the total consensus decision factor, it will mark the winner non domain solution. On each step, the dominate solutions are disregarded and only the non-dominate solutions remain on the process. The winner consensus solution for each case has an higher add value and a group gratification. It has a better quality and quantity dimension (financial and qualifying - industrial production environmental) when it is compared with the classic approach ones; or even with the last non- domain solutions, before the essential decision criteria(s) runs, it is more inventive and the decision process environmental sources can involve it. During the group discussion the risks are contested, valued and minimised when the final solutions (activities and reactions) are compared: they can be greater but they will be better analysed and measured by the rationality group consensus and the final solution is succeeded.