This paper deals with a new stochastic approach to handling data from waste biomass hydrothermal carbonization. The dynamics of hydrochar properties are described using the concept of reaction time distributions. A set of cumulative frequency distribution functions is provided that could very well correlate the most disparate experimental data. The procedure for analyzing the results is detailed. The method is illustrated with experiments on batch runs with five different wastes from the agro-food industry. Isothermal reactions (200 degrees C) were performed up to 120 min at a constant 7/1 water biomass ratio. The regression analyses fully confirm the correctness of the method. The use of dynamical van Krevelen plots is proposed. The approach allows also obtaining from lab-scale runs fundamental information for the correct waste -to-fuel process development at the industrial scale. The mathematics is not demanding and, unlike other methods, the difficulties substantially do not increase with the complexity of the modeled kinetic scheme. (C) 2019 Elsevier Ltd. All rights reserved.