Polyaniline/nylon 6 blends were prepared from formic acid as a single solvent with various weight ratios of polyaniline (PANI). The optical, structural, morphological, thermal, and electrical properties of these blends were investigated. Blend films with PANI protonated with sulfanilic acid (SA) as a new protonating agent showed higher conductivity and degree of protonation in comparison with unprotonated PANI. The PANI-SA/nylon 6 blend exhibited a percolation threshold at around 1.66 wt.% of PANI, whereas unprotonated PANI/nylon 6 blend appeared at round 10 wt.% of PANI. Schottky diodes based on PANI-SA and nylon 6 blend at different weight percentages of PANI were fabricated and characterized using Al as Schottky contact and Ag as an Ohmic contact.