The diffusion of polymers through the structural matrix of hybrid membranes was monitored using the fluorescently labelled polymer, PBd22-PEO14-TMR. This probe was incorporated in block copolymer containing membrane compositions (25-100 mol% polymer). The diffusion coefficient of PBd22-PEO14-TMR decreased with increasing polymer fraction, from 0.75 ± 0.25 µms -1 for 25 mol% PBd22-PEO14 vesicles to 0.67 ± 0.28 µms -1 in 100 mol% (single component) PBd22-PEO14 hybrid vesicles and 1.67 ± 0.52 µms -1 in 25 mol% PBd12-PEO11 hybrid vesicles to 0.71 ± 0.56 µms -1 in 100 mol% PBd12-PEO11 vesicles. Although the measured polymer diffusion through the hybrid membranes decreased with increasing polymer fraction in PBd22-PEO14 hybrid vesicles, this is not statistically significant between any pairwise comparison of compositions. This suggests that the polymer mobility is minimally affected by the lipid composition within the range studied. For PBd12-PEO11 hybrid compositions, the decrease between neighbouring compositions is only statistically significant (p < 0.05, Tukey and Bonferroni ANOVA) for the nearest neighbour compositions except between 50 mol% and 75 mol% PBd12-PEO11. Next nearest neighbour comparisons where significant (comparison of 25 mol% with 75 mol% and 100 mol% PBd12-PEO11 membranes, and 50 mol% with 100 mol%. This shows that for the smaller Mw polymer, the lipid composition has a greater impact on its mobility within the membrane than for the larger polymer.