An Electrospray Ionisation ion source and an Atmospheric Pressure Chemical Ionisation ion source are disclosed which comprise a probe 1 comprising two co-axial capillary tubes 2,3. A blue-flame gas torch 6 is provided downstream of the probe 1 as a combustion source. An analyte solution is sprayed from an inner capillary tube 2 of the probe 1 and a combustible gas is supplied to an outer capillary tube 3 of the probe 1. The combustible gas supplies heat to aid desolvation of the droplets emerging from the probe 1 via combustion with the surrounding oxygen-containing atmosphere when combusted by the blue flame torch 6.