Commercially available multiwalled carbon nanotubes (CNTs) were decorated by size-controlled and stable silver nanoparticles (NPs) using a sol immobilisation technique. Silver nanoparticles were in some cases protected by polyvinyl-alcohol (PVA). These materials were used to prepare different glassy carbon modified electrodes, which were tested in the electrochemical reduction of the anaesthetic halothane in two different solvents: water and acetonitrile. A different behaviour in the two different solvents is observed: silver nanoparticles are essential for the electrocatalytic activity in water while CNT are useless; in acetonitrile silver and CNT present a similar catalytic behaviour. The best modified electrode was used for the electroanalytical detection of anaesthetic halothane in both solvents. The use of PVA protective polymer for silver NPs allows better electroanalytical performances due to the protection from oxidation, fouling products and interferents. (C) 2014 Elsevier B.V. All rights reserved.