In this work, the effect of TiO 2 addition over morphological and ultraviolet (UV) blocking properties of poly(lactic acid) (PLA) and poly(E-caprolactone) (PCL) blends was investigated. The micrographs showed a partially co-continuous structure in the PLA/PCL blend with 42/58 (wt %/wt %) and the TiO 2 nanoparticles addition leads to a structural phase inversion, i.e., continuous PCL and partially continuous PLA with a dispersed portion. TiO 2 nanoparticles were observed to be preferably localized at the interface of the two phases due to kinetic effects (large difference between the melting temperatures) and nanoparticle geometry (low aspect ratios). An adhesion improvement between the phases and morphological stability were observed with the addition of TiO 2 nanoparticles. This behavior indicates that the nanoparticles can act as compatibilizers due to their localization at the interface between the two phases. The UV light absorption and transmission percolation threshold occurred with 1.5% TiO 2 in the 42PLA/ 52PCL blend.