Zákon o nabývání a pozbývání státního občanství České republiky
English version is also published on Wikipedia (slightly differs from Czech one):
Czech nationality law (The Czech Republic citizenship law)
Summary of the requirements for naturalisation:
1. The person has permanent residence in the Czech Republic ( usually recieved after 5 years)
2. Passed Czech language exam
3. The person has one of the following:
- has lived in the Czech Republic for at least 10 years continuously
- was born on the territory of the Czech Republic
- has held Czech citizenship before
- was adopted by a Czech citizen
- his or her spouse is a Czech citizen
- one of his or her parents is a Czech citizen
- has relocated to the Czech Republic before 31 December 1994 based on the invitation of the Czech government
- is stateless
- has the status of refugee in the Czech Republic
Czech version covers all the details, so please, read it here: Zákon o nabývání a pozbývání státního občanství České republiky or Google Translated version of the citizenship law can be found here: Act on the Acquisition and Loss of Citizenship of the Czech Republic
The documents necessary for the application are described in § 8 of the law. Administrative procedures are covered in § 10
