Born in 1961 in Bydgoszcz, professional education started at the Chemical Technical Highschool  (I. Łukasiewicz). He graduated from the Faculty of Chemistry at the Gdańsk University of Technology in 1986, defending the work on ion-selective electrodes. Subsequent studies were related to organic and siliconorganic synthesis and, from 2002 year on, to crystallography. The doctoral thesis concerned the Silanotiolanes of coinage metals (11th group of PTE), and the habilitation dissertation (2010) was a review of the structural analysis of silanethiolates and the impact of acid centres on the geometry of Si-O-C angles and Si-S bonds. He had been conducting studies of gallium(I) compounds at the University of Karlsruhe, Germany for one year as a postdok. Jaroslaw Chojnacki cooperates closely with the University UFPE in Natal, Brazil and with the Gdańsk Medical University. He directs the  X-Ray Structural Research Laboratory (founded by Prof. Wojnowski) at the Department of Inorganic Chemistry since 2002. He co-authored more than a hundred scientific papers. Since 2006, he has been an active member of the Polish Crystallographic Society. He promoted three doctors: PhD Andrzej Okuniewski (2015), PhD Agnieszka Brozdowska (2018) and PhD Damian Rosiak (2020). Since 2014 he holded the position of Associate Professor at  Gdańsk University of Technology and in 2019 avarded the title of full professor of Science and Natural Sciences from the President of Poland. On 2021 he organized (remote) IV Polish Crystallographic Olympiad as the head of Organizing Commitee under auspicies of Polish Academy of Sciences. On 2023 he conducted next (stationary) Vth edition of the Olympiad. He is a member of Polish Society for Crystal Growth and European Crystallographic Association. Hobbies: astronomy and classical guitar playing.