The ignition of natural combustible material by hot metal particles is an important fire ignition pathway by which wildland and urban spot fires are started. There are numerous cases reported of wild fires started by clashing power-lines or from sparks generated by machines or engines. Similarly there are many cases reported of industrial fires caused by grinding and welding sparks. In this work, the effect of metal type on the ability of hot metal particles to cause flaming ignition of powdered cellulose fuel beds is studied experimentally. The materials studied are stainless steel, aluminum, brass and copper. These metals are representative of clashing conductors (aluminum and copper) and those involved in machine friction and hot work such as welding (stainless steel and brass). Cellulose powder is used as a surrogate for natural fuel beds. Particles of various sizes from 2 to 11mm in diameter are heated to various temperatures between 575 and 1100° C and dropped onto the fuel bed. The results show a hyperbolic relationship between particle size and temperature, with the larger particles requiring lower temperatures to ignite the cellulose than the smaller particles. For large particles of all the metals, the ignition boundary is not very sensitive to particle size. For small particles the ignition boundaries are similar for the different metals and sensitive to both energy and temperature. The thermal properties of the metal play a lesser role in determining ignition with exception of the energy release from melting when it occurs. It also appears that the controlling ignition mechanisms by large particles are different than those from the small particles. The former appears to be determined primarily by the particle surface temperature while the later by the particle energy and temperature.