The airway surface liquid (ASL) adjacent to airway epithelial cells is crucial for normal respiratory function. The composition and volume of the ASL is governed by Na⁺ absorption across the epithelial cells. In human bronchiolar epithelial (H441) cells, this Na⁺ absorption is dependent on a K⁺ conductance that maintains the driving force for Na⁺ entry through apical ENaC channels (Inglis et al. 2007). This K⁺ conductance displays an interesting profile of being insensitive to barium yet sensitive to acid (pH6) and the local anaesthetic bupivacaine. These properties suggest that a two-pore domain K⁺ channel (K₂P) may be responsible for this conductance, with the acid-sensitive TASK-2 channel a likely candidate. We therefore cloned TASK-2 from H441 cells and stably expressed it in HEK-293 cells. The purpose of this study is to characterise the pharmacological profile of the conductance associated with the heterologous expression of TASK-2 in HEK-293 cells using electrophysiological methods. Whole cell patch clamp recordings revealed an endogenous outward current in untransfected HEK cells (18.1 ± 2.0 pA pF^-1 at 87mV, n = 33) under quasi-physiological conditions. This current is carried dominantly by K⁺ ions as raising [K⁺]_o (136mM) increased both inward and outward currents and depolarised the reversal potential (V_rev) in the manner predicted by the Goldman-Hodgkin-Katz equation for a selective K⁺ conductance. This endogenous current was insensitive to acid (pH6) with an inward current blocked by barium (3mM) and an outward current blocked by bupivacaine (3mM) and TEA (10mM). Heterologous expression of TASK-2 conferred an acid-sensitive outwardly-rectifying current onto HEK cells (43.2 ± 4.4 pA pF^-1 at 87mV, n = 22). Raising [K⁺]_o depolarised V_rev similarly to that seen with the endogenous current, confirming the current is carried by K⁺ ions. The outward rectification persisted at raised [K⁺]_o indicating the channel passes little inward current at very hyperpolarised potentials. The acid sensitivity allowed isolation of the current associated with TASK-2 and initial studies have revealed this acid-sensitive current to be insensitive to 10mM TEA. However, the magnitude of this current was only double that of the endogenous current and the complex nature of these native currents makes it a difficult model to characterise TASK-2.