This diploma is concerned with an analysis of the czech science fiction in a context of the 20th century with a regard to the period translations of english, american and soviet Sci - fi into Czech. The theoratical part will be devoted to a definition of the terms used in this work, mainly of term Science Fiction, with a try to a determination of a proper methodology of my research. There will be shortly dealed the progress of the american Science fiction in this part. The main content of this diploma will be an analysis of the speech of chosen texts from the era of the 30th till 80th years. In the conclusion there will be defined the changes of the language used in the genre of Science Fiction in a relation to the changes of epistemological horizon of the era based on these analytical probes.