Composite of multi wall carbon nanotubes (MWNTs) and silk fibroin were electrospun to nanofiber scaffolds with average diameter ranged from 46.2 to 100 nm. The effect of increasing the percentage of the MWNTs was evaluated on properties, characterizes and morphology of composite nanofiber scaffolds. Solution concentration, electric field, distance of needle from collector and flow rate were optimized for electrospinning. Optical and scanning electron microscope were used to study the morphology and diameter of composite nanofibers. The properties and characterizes were considered by using the FTIR spectroscopy, X-ray and Raman spectroscopy in addition, the electrical conductivity was measured utilizing Four-Point Probe method. Results showed that augmentation of the MWNTs had a small effect on the nanofiber surface. A growth was seen in the composite nanofiber diameter by increasing the MWNTs. Chemical interaction was not happened between MWNTs and silk fibroin based on FTIR spectroscopy and X-ray analysis also, crystallization of composite nanofibers grew by adding MWNTs. Raman spectroscopy proved that MWNTs were incorporated in the silk fibers. The electrical conductivity of composite nanofiber scaffolds was increased by increment of the MWNTs. (C) 2016 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.