The plastic crystal phase forming N-methyl-N-propylpyrrolidinium tetra fluoroborate organic salt P13BF4) was combined with 2, 5 and 10 wt.% poly(vinyl pyrrolidone) (PVP). The ternary 2 wt.% PVP/2 wt.% LiBF4/P13BF4 was also investigated. Thermal analysis, conductivity, optical thermomicroscopy, and Nuclear Magnetic Resonance (B-11, F-19, H-1, Li-7) were used to probe the fundamental transport processes. Both the onset of phase I and the final melting temperature were reduced with increasing additions of PVP. Conductivity in phase I was 2.6 x 10(-4) S cm(-1) 5.2 x 10(-4) S cm(-1) 1.1 X 10(-4) S cm(-1) and 3.9 x 10(-5) S cm(-1) for 0, 2, 5 and 10 Wt-%PVP/P13BF4, respectively. Doping with 2 wt.% LiBF4 increased the conductivity by up to an order of magnitude in phase II. Further additions of 2 wt.% PVP slightly reduced the conductivity, although it remained higher than for pure P13BF4. (c) 2005 Published by Elsevier B.V.