Computational toolkits are expected to deliver valuable and cheap support to optimise the processing and design of cementitious materials (in terms of mechanical performance or life-cycle analysis). Furthermore, the time and cost for quality control assessments is hoped to decrease significantly with the aid of such tools. In support of such development the micromechanical properties of cement-based materials are increasingly needed to assess their durability, predict/model their behaviour under different conditions and assist new materials development. This study was associated with the FP7 EU CODICE Project (COmputational Design of Innovative CEmentitious Materials, 2008 - 2011), which aimed to develop a multi-scale model for the computer based simulation of mechanical and durability performance of cementitious materials. In this research, extensive work on micro-/nanomechanical characterisation of cement-based materials was conducted, which covered synthetic C3S, C2S pastes, cement pastes hydrated at different ages and pastes subjected to accelerated calcium leaching. Statistical nanoindentation and micromechanical property mapping technique was used to study intrinsic properties of different hydrate phases (e.g. calcium silicate hydrates gel, or C-S-H) and microstructures down to approximately 1 μm. A major difficulty encountered in this work was to prepare representative test specimens with a low surface roughness. After substantial trials, a suitable methodology for preparing test specimens was developed, which allowed representative and reliable nanoindentation testing on early age and calcium leached cement paste specimens to be successfully carried out. Improvement in data analysis for the statistical nanoindentation technique was also implemented.