The electro-analytical sensing of Ketamine is reported for the first time utilizing [Ru(bpy) 3 ] 2+ as a Electrochemiluminescent reagent probe. The niche of this electro-analytical method is the lack of any sample pre-treatment as well as being cost and time effective. The methodology is shown to be useful for quantifying low levels, ng/mL, Ketamine in not only buffered solutions but also in an alcoholic beverage. We have successfully demonstrated the detection of Ketamine over a range of Ketamine concentrations 2000 ng/mL to 50 ng/mL in buffer solution. A linear response is observed (ECL emission/mV = 0.0098x+6.120, R 2 = 0.9915 and N = 5) with a detection limit of 33 ng/mL (based on 3-sigma). The proposed method was successfully applied to the determination of Ketamine in an alcoholic beverage sample -Gordon's Gin & Tonic. , is a synthetic, sedative, non-barbiturate, and fast acting anesthetic, which is able to block the receptor of N-methyl-d-asparate (NMDA) and is believed to affect opioid, adrenergic, cholinergic and serotonin receptors.1,2 Ketamine is a drug used in human and veterinary medicine, primarily for the induction and maintenance of general anesthesia, usually in combination with a sedative 3-5 (which is depicted in Figure 1).The increase in illicit use prompted ketamine's placement in Schedule III of the United States Controlled Substance Act in August 1999. 5,6 It became labeled a Class C drug on 1 January 2006 in the United Kingdom. 6 The recreational use of Ketamine has increased popularity worldwide over the last 10 years. 3,5 In fact, ketamine has surpassed other club drugs and even replaced heroin as the predominant drug of abuse in Hong Kong since the early 2000 7 with user experiencing hallucinations and a cataleptic state called the "K-hole." 5,6 Ketamine is generally analyzed by using immunoassays, 8 Liquid Chromatography-Mass Spectroscopy (LC-MS) 2,9,10 or Gas Chromatography-Mass Spectroscopy (GC-MS) 11-13 methodologies in biological matrixes. The drawbacks to these methods are that the times for the analysis are longer than 6 minutes per sample and a liquidliquid extraction prior to analysis is also needed.14-16 Tu et al. 8 reported an electrochemical impedimetric immunosensor for determining Ketamine in buffered samples. This method offers very low detection limits.Electrochemiluminescence (ECL) is an advantageous analytical tool, which is cost effective, portable and fast. [Ru(bpy) 3 ] 2+ is one the most important ECL reagents and the most widely used complexes for analytical investigations and applications owing to their excellent intrinsic characteristics. [17][18][19][20] It has been widely employed in biological matrixes, 21 pharmaceutical 22 and some drugs containing tertiary amine functional group 21,23-25 due to its continuance, sensitivity, reproducibility and selectivity toward many target analytes. 21,24,26,27 Generally, the amino group present in amine produces a secondary amine following by a dealkylation process in the presence of water. The radical cation of the ami...