The purpose of this thesis is to develop a mathematical optimization model to assist the authorities of the airport of Copenhagen in allocating the different companies in the check-in counters. This model should assign each company to specific check-in counters where the airline will provide passenger check-in services. The problem is complicated by the fact that a lot of conditions have to be considered. Due to the large influx of passengers and baggage, it is important to set a lot of constraints in order to succeed in terms of comfort, security and operational framework. These constraints are concerning to the physical layout of the airport, the available free space for queuing, the capacity of the conveyor belts used to transport the baggage and the operational requirements of the airlines companies. The objective is to fulfill these constraints and minimize the queue excess as well as the amount of baggage double screened. The model has been implemented in GAMS and tested with the real data of the 25th of June 2011. Key words: Check-in facilities, Airport of Copenhagen, optimization, Mixed integer programming (MIP), assignments, queue distribution, baggage management, counter allocation.