In our research, we deal with an important element of water cycle that is precipitation and its isotopic composition. Rainwater is formed by a number of complex atmospheric processes, in different clouds and under dynamic conditions, so it can be divided into two major groups: stratiform (drizzle, fog, rain, snowfall) and convective (shower rain, thunderstorm) precipitation. Atmospheric physical mechanisms give rainwater a characteristic isotopic composition, leaving traces of formation processes. The main goal of our research is to investigate the specific isotope composition of the two main rain types and their spatial and temporal variability. In order to achieve this, we are developing and operating a precipitation collection network in the Carpathian Basin and determine the isotope composition of the collected samples. Using the measured and observed data, we gain insight into the relationship between rainfall type and isotope composition.