As the third world most used fossil fuel and still demand is growing investments need to be made to keep up. Gas is a scarce and ending commodity. To facilitate trade in gas, large infrastructures like pipelines and storage facilities have been build in the past and needs to be build in the future. The EU mainly imports gas to meet demand. To improve trade they are liberalising the gas market as we speak. The Dutch own large gas reserve, which can still produce gas for up to twenty years. Due to supply disruptions like the Russian-Ukrainian gas crisis, questions rise whether supply securities of EU countries, and in this case in special The Netherlands, are sufficient. The Dutch have been self-sufficient since 1963 due to the discovery of a large gas field in Groningen. In the present The Netherlands is aiming at being the gas hub of north-west Europe in the future. To do this they invest in infrastructure and storage facilities. Due to the liberalisation, scarcity and the possibility of gas emergencies/disruptions this research tried to find out whether The Netherlands its long-term gas supply security worsened or not in past decade. To do this a model from the Energy research Centre of the Netherlands is used (ECN). This model was used to indicate the supply security of all primary energy sources. The model looks at import dependence, social and political stability and depletion rates to measure supply security. When looked at their home depletion rates concluded is that the supply security worsened over the past decade. Taking a closer look at the input variables, shown is that variety and balance of the imports for The Netherlands improved over the past decade. This was mainly due to the change in gas supplying countries. Due to this change the depletion rates of imports did improve significant. Although the model did not cover all aspects of supply security, it does give a good indication for the long-term supply security. Nevertheless it is still important to look to other information besides a certain model to fully capture the essence of supply security. In Chapter one an introduction is given about the gas market with respect to supply security. Chapter two covers the problems concerning long-term gas supply security. The next chapter state the research question and hypothesis. In chapter five the methodology is discussed followed by the results in Chapter six. Chapter seven there is some discussion about the used model. Chapter eight summarized the thesis and its conclusion.