A comprehensive trajectory model, Atmospheric Chemistry and Deposition model (ACDEP), has been developed to calculate the nitrogen deposition to the Danish sea waters. The model is constructed with the ability of taking into account spatially detailed emissions and land use data for Denmark and on a more coarse grid for the rest of Europe. In the ACDEP-model a one-dimensional column is advected along 96 h back-trajectories. The chemical mechanism in the model is a slightly extended version of the Carbon-Bond Mechanism IV (CBM-IV). The model describes the dry deposition processes with special emphasis on the conditions at sea. For the wet deposition processes both in-cloud and below-cloud scavenging are taken into account. The model results are tested versus one years measurements from six Danish and one Swedish monitoring station. Additional tests are performed for six selected stations from the European Monitoring and Evaluation Programme (EMEP) networks. The model is capable of reproducing both air concentrations and wet depositions of the nitrogen compounds in land and sea areas.