ABSTRACT: The ISSOP project (integrated system of runoff processes simulation) enabled the authors to analyze runoff and recession in a great number of small and medium catchments with differing geological backgrounds. Recession coefficient a was adopted as the spatially distributed parameter for base flow modeling in the ISSOP project`s hydrologic model development. This coefficient forms part of the equation S = aQb, which describes the nonlinear relationship between base flow Q and water storage S in a catchment. The characteristic a values were determined by master recession curves (MRC) for 293 small or medium mountainous catchment areas in Slovakia. Relationships of the recession coefficient and catchment characteristics were then examined by multiple regression analysis, and statistically significant dependencies of a value on the catchment mean elevation H and catchment slope were found. While catchment characteristics for the entire set of the catchments are able to explain only about 50 % of the recession coefficient variability, higher correlation was found for two of the eighth catchment groups, represented by crystalline rocks and carbonates. The influence of remaining six different basic types of hydrogeological environment was lower and almost similar.