An in-situ plated tellurium film electrode at the glassy carbon substrate (TeF-GCE) was applied for a sensitive catalytic voltammetric determination of molybdenum in the presence of 0.08 mM of mandelic acid (HA), 0.1 M of KClO3, 0.01 M of HCl and 150 mu g L-1 of Te(IV). The performed cyclic and square-wave voltammetric measurements indicate that the investigated catalytic system at the TeF-GCE involves electrocatalysis of the second kind, in which a composite complex between the catalyst Mo(V)-A and ClO3- ions forms, and the subsequent irreversible electrochemical reaction yields the catalyst and electroinactive ClO2- ions. The applied analytical procedure was based on 120 s of deposition of Te film at similar to 0.6 V, followed by differential pulse polarization of the electrode from 0 V to similar to 0.6 V. The sensitivity of the method was 4.02 mu A/(mu g L-1) and the catalytic voltammetric response was proportional to the concentration of molybdenum within the range from 0.02 to 0.14 mu g L-1. The limit of detection was found to be 0.004 mu g L-1 of Mo(VI), which makes the catalytic voltammetric method suitable for the quantification of Mo ultratraces in surface waters. (C) 2018 Elsevier Ltd. All rights reserved.