Complex heterogeneous materials offer unique combinations of mechanical, thermal, and functional properties resulting from their intricate microstructures. Accurate multiscale modelling is key to understanding their behaviour, predicting their performance, and enabling their optimisation in advanced applications [1]. In recent years, major advances in deterministic and stochastic methods have made multiscale modelling an expanding research area [2]. This Minisymposium will highlight recent progress in advanced analytical and computational tools for studying complex heterogeneous media, with emphasis on rigorous deterministic approaches and developments in stochastic and data-driven modelling. Topics of interest include, but are not limited to: • Advanced analytical and computational methods for deterministic and stochastic modelling of organised/random microstructures and fracture/damage evolution • Random field modelling of heterogeneous media • Design and optimisation of composite materials and structures under uncertainty • Scale-bridging techniques, including analytical and computational homogenisation and multiscale finite element methods • Multiphysics modelling of heterogeneous materials, including coupled mechanical, chemical, thermal, and electrical processes • Machine learning, data-driven techniques, and high-performance computing for efficient multiscale material analysis [1] T. Sadowski and P. Trovalusci, Multiscale Modeling of Complex Materials, 556, Springer, 2014. [2] G. Stefanou, D. Savvas and M. Papadrakakis, Stochastic finite element analysis of composite structures based on mesoscale random fields of material properties, Comput. Methods Appl. Mech. Eng. 326 (2017) 319-337.