In this paper, we test the price clustering theory in the crude oil futures market. Our novelty is that we consider the psychological barrier effect on price clustering and its determinants in the crude oil futures market. We find that prices tend to cluster on zero and five three weeks before the crude oil price reached the $100 per barrel mark and three weeks after the price rise. However, in the post- $100 price period, price clustering declines. We examine the determinants of price clustering and fmd that while size, volume, tick volume, and volatility have similar effects in terms of sign and significance in both periods, the spread variable is only significant (and positive) in the post-$IOO rise period. The general decline in price clustering and the significance of the spread variable suggests that once a price psychological effect elapses, traders in the crude oil futures market behave differently than when the price approaches a high price level.