Nanocomposites of polystyrene (PS) varying in molecular mass (PS1, PS2) and differently functionalized multiwalled carbon nanotubes (MWCNTs, 0.1-5.0 wt%) were prepared by melt and solution mixing. As fillers, pristine MWCNTs, phenyl propane ester and polystyrene functionalized MWCNTs as well as an in situ synthesized polystyrene masterbatch (DPS) were used. Functionalization procedure and characterization of functionalized MWCNTs are described. Dispersion ofMWCNTs as well as electrical, thermal and rheological properties of the nanocomposites were analyzed. Independent of the preparation procedure, the best MWCNT macrodispersion is achieved using DPS. When using solution mixing, the difference in macrodispersion between different MWCNTs is less pronounced in comparison to melt mixing. Solution mixed nanocomposites exhibit lower percolation thresholds in a similar range (PS1 < 0.20 wt%; PS2 < 0.30 wt%) whereas among melt mixed nanocomposites DPS shows the lowest electrical percolation threshold (PS1 0.27 wt%; PS2 0.49 wt%). (C) 2017 Elsevier Ltd. All rights reserved.