Biogas is a renewable fuel which can be used in numerous engineering applications such as heating, combined heat and power (CHP) generation and transportation. Biogas is a low calorific value gaseous fuel with low burning velocity, both of which make the burning and combustion stability of biogas a real challenge. This drawback of biogas combustion, especially under high flow velocity applications, restrains its industrial implementation. The present thesis aims to experimentally investigate the effect of burner exit geometry on the stability of a premixed biogas flame. The test burner consists of a central bluff-body surrounded by an annulus through which a swirling premixed biogas stream discharges into an atmospheric combustion chamber. Two different burner geometries were tested; a 43.5 mm long cylindrical or conical with an angle of 15 degrees, with the bluff-body was either flushed with the exit of the burner or recessed. Swirl strength was varied by changing the swirl generator’s vanes angle (25-degree or 60-degree, which represent a swirl number, S, of 0.39 or 1.16, respectively). The biogas surrogate composition is kept constant (75% CH4 and 25% of CO2). The results showed that attached biogas flames were observed at all test conditions explored in this thesis. The results revealed that the conical burner promotes higher flame divergence than the cylindrical one, and hence becomes in direct contact with the burner inner wall. The experimental results also showed that recessing the center body, when using a cylindrical burner geometry, enhances flame stability. Whereas, the opposite scenario happens when using a conical burner geometry. The effect of burner configuration (cylindrical or conical) on premixed biogas flames stability is found more significant at high swirl number.