As a part-time student, he completed his university studies in chemical technology at the University of Maribor in 1988. In 1990, he continued his postgraduate studies there as a young researcher and assistant, received his master's degree in 1993, and later his doctorate in 1997.
From 1989 to 1992, he continued his professional career at the University of Maribor as a young researcher and later as an assistant at the Faculty of Chemistry and Chemical Technology.
In 1992, he was employed by the municipal administration of the then Ptuj Municipal Assembly as a research and development consultant. Among the important results from this period is the establishment of the public scientific research institute ZRS Bistra Ptuj. As the first director, he led the institute between 1994 and 2002.
In 2002, he was elected mayor of the City of Ptuj in direct elections and led the municipality for three full terms. During this time, significant investments were made in Ptuj, including in the fields of science, education, economy, tourism, trade, economic and environmental public infrastructure, healthcare, culture and sports.
Among the more important investments is the renovation of the barracks for the needs of higher and higher education, and many others. After completing his mayoral duties in 2012, he again took over the management of the public institution ZRS Bistra Ptuj and strengthened it in terms of personnel and finances to the point that, according to international quality indicators, it ranks among the best regional development institutions within the European area.
In addition to professional articles published in foreign and domestic scientific journals, he is a co-author and co-owner of several patents.
Dr. Štefan Čelan has been collaborating with the University of Ptuj since 2012 and is the lecturer of two courses, namely; Biodiversity and Sustainable Development and Degradation and Reuse.