The self-assembly and phase transition diagrams of cellulose nanowhiskers derived from tunicates, food grade bacterial cellulose (nata-de-coco) and lab cultured bacterial cellulose are reported. The phase transition diagram for isotropic to liquid crystalline phase transition has been developed for cellulose nanowhiskers obtained from all these sources by recording phase separation behaviour and polarised optical microscopy (POM). The phase separation stops at 10, 4, and 12 wt% for tunicate cellulose, food grade and lab cultured bacterial cellulose, respectively, which also corresponds to the transition seen by POM. The phase diagrams and transition behaviours are explained on the basis of aspect ratio distributions. The liquid crystalline phase obtained after transition shows characteristics of both nematic and chiral nematic phases. (C) 2013 Elsevier Ltd. All rights reserved.