<p>Ten unexpected organic compounds from the variety of preparations of cyanoximes were isolated and then identified using only single crystal X-ray analysis due to scarcity of those side products. Intended and targeted cyanoximes were obtained as well, but other compounds being evident products of unwanted and unintended side reactions were found during chemical syntheses. Cyanoximes demonstrate a wide range of biological activity and are now currently developed as novel cytotoxic and antimicrobial agents. The knowledge of structures and ways of formation of side products becomes of critical importance. Tentative mechanisms of formation of these undesired compounds are provided. Crystal structures of all ten identified products of side reactions of syntheses of cyanoximes using the Meyer reaction are presented and discussed in this work.</p> Graphical abstract <p>Ten unexpected organic compounds from different preparations of cyanoximes were isolated and identified using single crystal X-ray analysis.</p> <p></p>