Bulk solids are exposed to time-dependent mechanical stressing due to particle-particle and particle-apparatus contact interactions during various manufacturing processes and transportation steps. These interactions can be described by discrete element method (DEM) based on the contact models of particles. Usually in DEM simulations the particles are assumed to be spheres and as a consequence shape effects are neglected. However, most bulk solids processed in industry consist of irregular shaped particles. Therefore, in order to improve accuracy of numerical simulation the real shapes of particles must be considered in DEM. In this work, amorphous irregular shaped micrometer-sized titanium dioxide agglomerates were investigated. The force-displacement curves at compression were obtained with the help of a self-designed experimental setup. Based on the experimental data, several material parameters were determined and implemented in viscoelastic and elastic-plastic contact models. To consider the shape effect in the estimation of contact parameters the DEM simulation of studied agglomerates was performed by multi-sphere approach and bonded-particle model. The shape and position of the agglomerates on the loading pin were obtained by X-ray computer tomography and used in DEM simulations. From the obtained results it was pointed out that the bonded-particle model based on Maxwell viscoelastic model gives the best agreement with experimental data from compression tests with titania agglomerates. (C) 2015 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.