PdO-decorated SnO2 nanocomposites with open porous hierarchical architectures are fabricated through a facile biotemplating sol-gel technique. The sol-gel soakage process is carried out by immersing the templates butterfly wings in Sn- and Pd- impregnants successively to generate a uniform colloid layer. PdO and SnO2 nanocrystallites come into being with subsequent calcination treatment, and PdO-decorated SnO2 nanocomposites further construct the parallel main ridges with connective pillars and vertical struts, finally present a 3-D open porous hierarchical architecture. Benefiting from unique ingredients and structure hierarchy, the nanocomposites give enhanced acetone-sensing performance of high sensitivity and rapid response/recovery rate