Thujone is a ketone and a dicyclic monoterpene which naturally occurs in a variety of common plants, but in large quantities may be toxic for humans. In this work a simple and rapid DPV methodology of thujone determination on renewable silver amalgam film electrode is proposed. It was observed that the reduction of thujone in nitric acid is a quasi-reversible two-electron process, while the reaction was controlled by surface phenomena. Experimental conditions such as composition of the supporting electrolyte and operation parameters were optimized. The promising results were obtained in 0.0115 mol L-1 HNO3 (pH 1.85) and 9.6% ethanol. The calibration graph was linear from 0.7-142 mg L-1 with correlation coefficient r = 0.9996. Obtained sensitivity was 0.0724 mu A/mg L-1, while detection limit 0.05 mg L-1. In the presence of copper the sensitivity was reduced to 0.0504 mu A/mg L-1. Procedure was verified using complex herbal matrices spiked by the thujone. Recovery of the low analyte concentration i.e. 0.7-2.1 mg L-1 significantly depends on the level of the interferences. A self-referencing strategy of thujone determination in thuja oil was also developed and applied in exploration of thujone without preparation of the sample in commercially available product.