Jiri Trnka (1912 - 1969) ranks among the foremost representatives of Czech modern art in the 20th century and alongside the most remarkable protagonists of the visual art scene over a period ranging from the late 1930s through the end of the1960s. He stood out within that movement for his multiple talents, as a draughtsman, book illustrator, puppet designer, painter, animated film-maker, sculptor and stage designer. He achieved admirable success in these fields of activity. In the early 40s a new prospect opened up for him connected with work in theatre, as he took up the post of stage designer at the National Theatre in Prague, an assignment which enabled him to put to use his specific talent for stagecraft. He created 13 stage decorations together. Trnka was able to create unforgettable productions thanks the cooperation with Jiri Frejka or Karel Dostal. I documented and explained Trnka's work in the context of the Nation Theatre during the Second World War. I defined his style in the relation to his contemporaries in the end of work. KEY WORDS Jiri Trnka, National Theatre, set designer, scenography, stage decoration, costume, properties, scene, 40s, space, stage, style, set, constructed set, stage design, didascalia, theatrical space, animated film.