In this thesis, a method for the analysis and characterization of the timetable offer in public transport is developed and applied to the example of Slovenia's rail passenger transport services along the time series from 1975 to 2015. Based exclusively on the timetable data along the main lines between Ljubljana, Maribor and Zagreb, the time series is examined through the punctual evaluation of ten timetable years. The analysis follows a passenger perspective and focuses on direct train connections along every origin-destination (O-D) relation within the area of interest. The timetable offer is characterized by a multivariate analysis with two levels of detail. In a first step, a cluster analysis based on the k-means algorithm is used to group the O-D relations depending on the similarity of their overall timetable characteristics. In this step, the number of trains per day, the regularity of the timetable as well as the regularity of the travel time are the indicators considered. In a second step, six exemplary relations with a higher level of detail are examined, where travel speeds, train headways and the timeframe of the trip offer are included in the analysis. The results show an overall increase of the quality of the rail transport supply. The greatest proportion of this expansion took place between the 1970s and 1990s, while in the period from 2000 to 2015 only relatively few changes could be identified. In regional traffic, a very dense offer was developed within the wider urban areas of Ljubljana, Celje and Maribor. At the same time, the train numbers also increased along the Ljubljana Zidani Most, Maribor Zidani Most and Dobova Zidani Most sections of the track. However, the rail triangle in Zidani Most sets a territorial limit to the supply levels of direct connections of regional trains. Regarding the intercity connections, it becomes clear that a direct cross-border link to / from Zagreb is not prioritized by the timetable offer. While Zagreb and Maribor have low train numbers along the entire time series, their reduction between Ljubljana and Zagreb takes place in parallel to Slovenia's independence. During the time series, the intercity connection between Ljubljana and Maribor was initially expanded to a regular and supply-oriented interval timetable, before a slight reduction in train numbers renewed a tendency towards demand-oriented timetable planning from the year 2000 onwards.