Of special importance in all national literatures, including in Croatia, is literature intended for children's readers. Kušan is the founder of the contemporary Croatian children's novel, and during his lifetime he was proclaimed a Croatian children's classic. Kušan's first novel, Uzbuna na Zelenom Vrhu, was a turning point in Croatian children's literature and the complete opposite of Lovrak's novels. Kušan approached the children's novel in a new way by removing the politicization of children's literature. Erich Kästner's great influence is visible in his work, but also the beginning of a new era of children's novels. Namely, he places the plot of his first novel in the period when the war ended, but he does not write about war heroes, which was a novelty at the time. This paper will analyze all of Kušan's novels in which the character of Koko is present: Uzbuna na Zelenom Vrhu (1956.), Koko i duhovi (1958.), Zagonetni dječak (1963.), Koko u Parizu (1972.), Ljubav ili smrt (1987.) i roman Koko u Kninu (1996.). At the beginning, the concept of the novel will be explained and an overview of events related to its development will be given. Furthermore, Kušan's significance in literature will be explained, characters and their relationships will be characterized. The terms intertextuality and authorial referentiality will also be explained.