The syllabus is in
http://easa.europa.eu/agency-measure...20Part-FCL.pdf in the relevant section for the licence you are going for. Eg p39 for LAPL.
However if you're wanting to do the theory to get a flying licence then go buy the text books. You need to know pretty much everything it says in them. There are a number of different series of them which have been well discussed here before.