Cyber-attacks have increased since the 1988-Morris worm and can target any connected device from any place in the world. In 2010, Stuxnet received a lot of attention as the first cyber-weapon. Its targets were the Iranian nuclear enrichment centrifuges. Nation states are developing cyberspace capabilities to conduct offensive cyberspace operations. Academic researchers have been calling for a more transparent discussion on offensive capabilities and have pointed out the positive impact researchers had during the development of nuclear capabilities. Shrouded in secrecy, the development of offensive capabilities used for operations makes it difficult to conduct research. Therefore, one way to mitigate this is to conduct a systematic review of the current state of research in offensive cyberspace operations. The systematic review method makes it possible to establish certain inclusion and exclusion criteria and systematically go through academic articles to identify the contents, thoughts and research focus of academic researchers. Six scientific databases were queried and 87 articles were read and clustered. The first insight is that, based on the results of the queried databases, research about offensive cyberspace operations is limited. The resulting clusters are a general cluster about cyberspace operations, followed by research in policy, decision-making, governance, capabilities, levels, models, training, deterrence and international affairs. These are then further grouped into: a) general cyberspace operations; b) deterrence; c) international affairs; d) modelling, simulation and training. The article concludes that research into offensive cyberspace operations is maturing as more information is becoming public. Secondly, current research lists some good basic ideas regarding effects which can be achieved through offensive cyberspace operations, how they should be conducted, and related tools, techniques and procedures. However, discrepancies in research efforts exist, with the majority of research coming primarily from the western world. In addition, secrecy and the resulting limited access to information, coupled with research being either too technically focused or too qualitatively focused, show that there still remains room for research in this field. Finally, some directions for future research are examined.