Flames in narrow clearances are studied by using a spectral infrared imaging method and some of the results are reported herein. The spectral band employed in the method is a 2–2.5 micrometer band, which is to capture the spatial and temporal distributions of radiation emission from water vapor present over the flame fronts. The infrared radiation image was obtained using our new high-speed imaging system which enables us to achieve a framing rate of over 1,800 frames/sec with exposure period of as short as 20 microseconds that employs a 64 × 128 PtSi Schottky barrier imager. The infrared images of water vapor emission from flames in narrow clearances offer some new findings not attainable in the previous schlieren cinematographic imaging.