The adsorption of arsenic from aqueous solution using activated carbon fiber (ACF) was investigated. Several series of experiments were conducted to investigate the effect of operating parameters such as equilibrium time, flow rate, and initial concentration that affect to the adsorption rate. Average removal efficiency was 24% for the initial arsenic concentration of 10 mg/L to 17 mg/L. Breakthrough point in ACF unit reached at 5 hours of the experimental operation for aqueous solution containing arsenic. Adsorption capacity of the filter was found to be 0.18 mg/mg of ACF. With the increase of flow rate there was a slight increase in the removal of arsenic. Field tests from thirty contaminated sites in Sonarang, Bangladesh have shown that the arsenic removal efficiency was only 13.0% in the single ACF unit, while it was increased upto 24.6% in two ACF units in series. Among the several fitting regression curves tested, three dimensional non-linear regressions gave over 90% fitting, while for other linear regression curves it was in the range of 5 to 92% depending upon the various operating parameters. Non-linear models described the relationships of C with C(0) and t better than the linear ones, and this model gives a good generalization of the kinetics of arsenic in ACF for the laboratory tested ranges.