Bioenergy has received less attention in recent times due to its changing negative image. For the EU, bioenergy was considered mostly for its contribution to greening and diversifying its energy mix. While its impact on CO2 emissions is hotly debated, there is a dearth of studies regarding the energy security implications of bioenergy in the EU. This opens up a window of opportunities and challenges to perform such a study. The main research question of this thesis is:What has been the impact of bioenergy on the energy security for the EU from 2000 to 2018?The main research question and the sub-research questions are addressed in the context of the EU economy and its vision for climate mitigation. The thesis starts with the literature review of energy security leading up to framing a new theoretical framework. Past implications of bioenergy that includes biofuels in the last decade and a half since 2000 have been analyzed. The thesis has assessed what bioenergy has delivered in that time. Positive and negative developments are taken into account and analyzed with respect to the selected energy security indicators and metrics.Both ES literature and PEST tool have been employed to narrow down the data gathering and relevance of energy security indicators for bioenergy. The use of the PEST analysis tool also offers a unique combination of elements in the framework and a boarder categorization, which in traditional energy security is often not employed.To get a better overview of EU bioenergy, a review of the current policy of the EU for bioenergy has been done. It presents all relevant data related to bioenergy like various bioenergy potential, total energy consumption, and demand, etc. Then, different characteristics and features of bioenergy are described along with the various conversion routes to obtain different forms of energy (namely biofuels, bio-electricity, and bio-heat) are explained. Some of the projections for 2020 for bioenergy in the EU have also been provided to better gauge the state of availability of resources and likely policy direction taken in the future. The effects on the energy security indicators of bioenergy in the EU have been derived from the data on EU bioenergy and is assessed with respect to the 22 selected energy security indicators and metrics from the analytical framework. A rating of 3.0 here implies no or a little effect for energy security indicator or metric on account of bioenergy, anything above 3.0 is positive, and below 3.0 implies a negative impact. It is found that the overall effects have been slightly positive with an average rating of 3.09 for all the 22 selected ES indicators. With 3.5, for the dimension of ‘technology development and efficiency’, it has a positive effect implying an increase in employment in the bio-sector and high research budget for bioenergy from 2000-2018. However, with a score of 2.9 for the dimension of ‘Environmental & social sustainability’, the effects have been overall negative, implying a negative impact on the environment in the last 18 years.