Abstract. In the framework of the regional analysis of hydrological extreme events, a probabilistic mixture model, given by a convex combination of two Gumbel distributions, is proposed for rainfall extremes modelling. The papers concerns with statistical methodology for parameter estimation. With this aim, theoretical expressions of the L-moments of the mixture model are here defined. The expressions have been tested on the time series of the annual maximum height of daily rainfall recorded in Tuscany (central Italy).