In this research raw date palm trunk fibers were used to adsorb cadmium ions from aqueous solutions. The date palm trunk fibers are considered as agricultural waste which is available in huge quantities in the Kingdom of Saudi Arabia. In order to assess the feasibility and the efficiency of using this as an adsorbent, a series of experiments were conducted in a batch adsorption method. The effects of the process variables such as fiber size, mixing rate, mixing time, temperature, solution pH and adsorbent dose on the adsorption capacity of date palm fibers were studied. The results obtained indicated that the adsorption capacity of Cd2+ increased from 29.06 to 51.1 mg/g as the particle size decreased from 875 to 100 μm. It was found that the adsorption capacity of Cd2+ decreased in the strong acidic medium and increased rapidly as the solution pH increased from 1.69 to 3.71. The adsorption capacity was observed to have an insignificant change on raising the temperature from 12 to 34 °C and increasing of mixing speed from 100 to 500 rpm. Also, one very important finding of this research is that the equilibrium time of the adsorption process is very short. The maximum adsorption capacity was obtained after 10 minutes.