Abstract: In the context of the extensive collection of works by the architect Károly KÓS, the article examines the transformation project of the Calvinist church from the village of Periș (In Hungarian: Körtvélyfája - Mureș County) designed and executed between 1949 and 1950. The church is currently undergoing restoration and conservation interventions which allowed the authors of the article to have a deeper understanding of the development of this object and to understand its place in the Transylvanian architect's body of work. The church is analysed from several perspectives - architectural language, aesthetic choices and dialogue with Transylvanian historical models. The intervention is placed in relation to other works of a similar nature by the architect, some executed, others remaining on paper, both equally important. The article briefly reviews the relevant projects for outlining the specifics of the intervention in Periș. Finally, the paper aims to deepen the knowledge of this less-known but relevant object of worship as an example of intervention in the last part of the career of Károly KÓS, in the service of the Reformed Diocese of Transylvania.

Keywords: Károly KÓS, transformation, restoration, built heritage, Calvinist church of Periș