Settling bed oil shale retorts can be operated on a small scale without internal equipment (such as air distributors) provided that there are sufficient instruments and controls to determine what is happening in the retort, permitting adjustment of the various flow rates. Variation of retorting rate from 38 to 73 m/d had little effect upon the oil yield or properties. Decreasing the air content of the feed gas reduces retorting temperatures and heating rates, which results in less mineral carbonate decomposition, less organic char reaction, lower oil pour points and lower oil viscosities. Problems in solids flow occur using finer shale particles, due presumably to excessive oil holdup and coking.