Multi-line NO-LIF temperature imaging was applied to measure two-dimensional gas-temperature fields in a lowpressure, premixed flat-flame nano-particle generator. This was the first time this new technique was applied in a low-pressure combustion system. Flame temperatures between 1500 and 700 K were measured in a 175 × 50 mm field with a precision of ±1 %. The data are of great use for the simulation of nano-particle formation based on kinetic modeling. Pressure effects on the flame structure and stability were investigated. The laser fluence was controlled in order to avoid saturation of the LIF signal, which occurs above a fluence of 12 kW/cm2 at reactor conditions and influences the temperature results.