This paper reports the characteristics of LPG diffusion flames in a swirl burner in which the swirling air flow is generated by three spiralling air jets issuing from the helical grooves. The performance of the helical swirl burner (HSB) is compared with a conventional tangential-slot swirl burner (TSB) of the same diameter and under identical amounts of fuel and air flow rates. The data obtained for the two burners on flow velocity components, static pressure and central recirculation zone in isothermal flow and flame stability and flame temperature mapping have been presented. It is observed that the HSB produces higher swirl intensity compared with the TSB at the burner exit. The geometry of the central recirculation zone analyzed in the two burners indicates that the average residence time is higher in the HSB than in the TSB. Additional study results are discussed.