Abstract: A flame detection system comprising two light responsive photovoltaic photocell sensors in combination with corresponding light filters, a photovoltaic sensing amplifier, a control amplifier, and a power source. The photocell/filter combinations are responsive to spectral energy in two different regions of the spectrum, said regions being such that illumination from a hydrocarbon flame causes a reversal in voltage polarity of the signal from the pair of photovoltaic photocells. The photovoltaic photocells are serially connected in voltage opposition and the voltage produced by the combination is applied as an input coupled to the sensing amplifier. The latter is arranged and configured to respond to a selected voltage polarity generated by the photovoltaic combination, when illuminated by a hydrocarbon flame, by providing a control signal to the control amplifier. The control amplifier is typically coupled to a relay and/or solenoid valve which controls the turn-on of a fire alarm and/or extinguishing means.