According to National Statistics Approximately 1.35 billion gallons of used oil are generated yearly. With the increasing of the concrete usage, a more cost effective and economic new type of admixtures may give positive impacts on the Malaysian construction building as well as worldwide concrete usage. To objective of this is study is to investigate the effect of used cooking oil in terms of slump test, compressive strength test and rebound hammer. By adding the used cooking oil to the concrete, it increases the slump value from 4% to 72%. And the compressive strength have an increment from 1% to 16.8%. The used cooking oil obtains the optimum contribution to the concrete mix proportion of containing used cooking oil of 1.50% from the cement content. The result of used cooking oil from experimental program of slump value and compressive strength proved that used cooking oil have positive effects on replacement of commercially available superplasticizer.