This article presents novel solvent cast biocomposites of poly(lactic acid) (PLA), polyhydroxybutyrate-co-valerate (PHBV), and polycaprolactone (PCL) with enhanced barrier properties to UV light, oxygen, water, and limonene by means of incorporating an organomodified mica-based clay grade. The TEM results suggested a good clay dispersion but with no exfoliation in the three biopolyesters. In agreement with the crystallinity data, which was found to generally increase with increasing filler content, oxygen but specially water and o-limonene permeability coefficients were seen to decrease to a significant extent in the biocomposites and an optimum property balance was found for 5 wt % of clay loading in the three biopolymers. With increasing clay content, the light transmission of these biodegradable biocomposites decreased by up to 90% in the UV wavelength region due to the specific UV blocking nature of the clay used. As a result, these new biocomposites can have significant potential to develop packaging films, coatings and membranes with enhanced gas and vapor barrier properties and UV blocking performance. (C) 2010 Wiley Periodicals, Inc. J Appl Polym Sci 118: 188-199, 2010