The mixograph is a planetary pin mixer that has been used for decades to evaluate the mixing tolerance and large strain rheology of hydrated flour. in this work, computational fluid dynamics (CFD) has been used to gain greater understanding of the mixing action of this mixer by evaluating both local and global measures of mixing using particle tracking. in this study, mixing of a highly viscous, Newtonian corn syrup is simulated. Segregation scale, length of stretch and efficiency are used to evaluate the mixer. It is shown that this planetary pin mixer does not experience as much axial mixing as cross-sectional mixing over the same time span. Additionally, it is observed that some pin positions are more efficient than others. These results are being used to compare this mixer with other mixers used for similar purposes in the food industry. (C) 2008 The Institution of Chemical Engineers. Published by Elsevier B.V All rights reserved.