The objective of this study is to increase mechanical, thermal, and electrical properties of plasticizer free thermoplastic bio polymer, BIOPLAST GS 2189 (BP), a blend of poly lactic acid (PLA) and potato starch. This polymer is highly suitable for sheet molding, film processing; blown film extrusion and injection molding and fully biodegradable. Structural, mechanical, thermal, and electrical properties of these films were manipulated by reinforcement of multiwalled carbon nanotubes (CNTs) in BP. Thin films of various (15 wt %) percentages of CNTs/BP were prepared by using a high-speed spin coating technique. These as-prepared films are approximate to 60100 mu m in thickness. The thickness measurements of these films were carried out using micrometry and optical microscopy. The maximum tensile strength (200%) and modulus (150%) was observed for 4 wt % loading of CNTs in BP as compared with the neat BP thin film. The X-ray diffraction results show that the addition of CNTs in BP increases the crystallinity of BP. Electrical conductivity of this film also increased by 48% as compared with the neat BP polymer films. (c) 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013