Biomimetic and slow solvent evaporation crystal growth methods were used to produce ibuprofen mesocrystals. Water and 2-propanol as well as water and ethanol were used as binary solvents, with the former yielding mesocrystals, but the single crystals were obtained with the latter solvents. The biomimetic method produced precipitates of ibuprofen whereas mother liquid left at different solvent ratios was used for slow solvent evaporation to produce mesocrystals. The single crystals results were used to compare the mesocrystals characterized by Raman, PXRD, SEM, TG/DSC, SAXS and in vitro drug dissolution studies (WP1). Different additives such as Hydroxypropyl methylcellulose (HPMC), Pluronic-F127, Polyvinylpyrrolidone (PVP), Polyvinyl alcohol (PVA), and Polyacrylic acid (PAA) and their amounts were varied to control the mesocrystallization. The carboxylic acid groups in both PAA and ibuprofen may initially form dimer which was controlled to stabilize the basic nanoparticle building unit to form mesocrystals. The other additives produced only aggregates of ibuprofen (WP2). The in vitro drug dissolution test was performed in phosphate buffer during the secondment period for the mesocrystals, precipitate and single crystals. The dissolution rate has enhanced for the mesocrystals compared with the single crystals. It was challenging to control the transformation of mesocrystals to single crystal thus the presence of undesired single crystals in mesocrystals may affect the dissolution rate. However, the enhanced dissolution rate due to this new mesocrystals strategy can retain the crystallographic features and properties as single crystals at the same time enhance the drug dissolution (WP3).The OMECRY project results were disseminated through different scientific conferences and invited talks (WP4), book chapter, news, research articles. The review work on organic mesocrystals will also be published.