Today, industrial and service robots are used all over the world to handle sim- ple repetitive tasks as well as more complex tasks. Many warehouses use robots for their logistical tasks, while warehouse employees only need to ensure that ev- erything is performing properly and finish some tasks like collecting items and shipping them out to customers. This thesis investigates how to reorganize a high density storage of stacks. Mul- tiple algorithms such as exhaustive, random and greedy searches were implemented on top of my own problem specific designs, and tested in simulations separated from the actual system. The results from implementations made during the work with this thesis were compared to each other and to the performance of today s system. The majority of the work in this thesis have been to design and implement my own ideas on how to solve the reorganization problem. During my work, much time have been spent to rethink, adjust and redesign the algorithms in order to get even better performance. Results from simulations of the various algorithms are promising, and improvements can be seen over the different implementations during my work. In comparison with how today s system performs on the reorganization task, the results are also very promising. However, the comparison of today s system and the implementations in this thesis have some uncertainties, and further work is required to confirm the improvement completely. The last chapter of this thesis contain useful suggestions on further work may improve the reorganization time even more.