The nanocomposite films of poly(3-hydroxybutyrate) (PHB) and poly(3-hydroxyoctanoate) (PHO) with single wall carbon nanotubes (SWCNTs), were prepared. The Optical microscopy showed that the crystalline size substantially decreased for PHB/SWCNTs nanocomposites with a 1 % weight fraction of SWCNTs relative to PHB (PHB/(1%)SWCNTs), indicating the effective nucleation of PHB crystallization by SWCNTs. Mechanical properties of the nanocomposite films were measured by nanoindentation. Both polymer nanocomposite films showed an increase in hardness (H) and Young's modulus (E), with SWCNTs concentration. The PHB/SWCNTs nanocomposite films are found to be more brittle than neat PHB films.