Cellulose is the most abundant biomass material in nature and finds a range of application. Cellulose microfibers were extracted from Hibiscus sabdariffa fibers by steam explosion technique. Structural and surface analysis of the microfibers showed a reduction in diameter and changes in surface morphology from that of the raw fibers. The chemical composition of fibers were analyzed according to the TAPPI standards and showed increase in α-cellulose content and decrease in lignin and hemicelluloses for the microfibers. This has been further confirmed by SEM, XRD and FTIR results. Thermal characterization showed enhanced thermal stability of celluloses microfibers compared to raw fibers.