Which pure metal in its solid form in oxygen has the highest ignition temperature in...

titanium is the pure metal in its solid form in oxygen that has the highest ignition temperature in degrees Fahrenheit.The spontaneous-ignition temperature of titanium in the solid phase (below melting) is about 3020°F (1660°C)1.Aluminum, potassium, and zirconium have lower ignition temperatures in the solid phase, ranging from 1292°F (700°C) to 1652°F (900°C)23.References:

IGNITION OF METALS IN HIGH PRESSURE OXYGEN2

Combustion of Metals in Oxygen-Enriched Atmospheres3

High-temperature oxidation and ignition of metals1