An experimental laboratory was conducted to treat produced water by kapok fiber adsorbent, activated using sodium hydroxide (NaOH) 5% wt. and hot water at 100 0C followed by ultrafiltration membrane to reduce total dissolved solids (TDS), barium, and phenol concentration. The research variables were operating times of 30, 60, and 90 min, and the flow rate of produced water samples was 5 L/min, 6 L/min, and 7 L/min. The scanning electron microscope (SEM-EDX) investigated the kapok fiber's surface. The results showed that the decrease in TDS, barium, and phenol by activated kapok fibers was 52.8%, 66.77%, 72.55%, respectively. Further, filtrate treatment from kapok fibers column in ultrafiltration membranes (UF) showed the removal of TDS, barium, and phenol removal achieved 43.12%, 99.76%, and 42.44% at a feed flow rate of 5 L/min and operation time of 90 min. The total removal for the currently proposed system is 95.91% TDS, 99.92% barium, and 84.20% phenol. Produced water pretreatment using kapok fibers absorbent followed by UF membrane reduce TDS, barium, and phenol concentration from produced water. Finally, the permeates of the ultrafiltration membrane followed Indonesian standards for wastewater quality.