IntroductionThe widespread use of heavy metals and their compounds by modern industries has led to the discharge of large quantities of this element into the environment. These inorganic micropollutants are of considerable concern as they are not biodegradable, are highly toxic and have a probable carcinogenic effect. If discharged directly into the sewer system, their presence decreases the effectiveness of the biological treatment [1, 2, 3]. Among heavy metals, chromium is one of the most important environmental problems. Most of the chromium is discharged into aqueous wastes as Cr(VI) and Cr(III). A wide range of technologies are available for the removal of Cr(IV) and Cr(III) from wastewater. Cr(VI) in liquid waste is more dangerous than Cr(III). Removal of Cr(VI) is more difficult than Cr(III). The removal of Cr(VI) from liquid waste has been conducted by various researchers, for example via an adsorption process using chemicals as adsorbents. The use of chemicals as adsorbents is not environmentally friendly. Therefore, you need to look for another environmentally friendly alternative adsorbent. The use of biosorbent to absorb heavy metals such as Cr(VI) is very promising because it is environmentally friendly. Numerous researches have used biosorbent for the treatment of wastewater containing Cr(VI). Sudiarta [4] uses algae to absorb Cr(III), Aprilia Susanti [5] uses peanut peels as a biosorbent to absorb Cibacron Red reactive dyes, and Ajeng et al [6] uses chitosan from crab shells to absorb copper ions. Sutrasno et al. [7] conducted research using guava bark to absorb Cr(VI) metal ions. The obtained results showed that the adsorption efficiency of Cr(VI) is more than 90% at pH 2. This research uses ...... half of the paper ...... of Pseudo-Second-Order to Cr(VI) Removal with a biosorbent dose of 1 gram. Based on Figures 3 and 4, it can be concluded that the Cr(VI) adsorption process using guava leaves follows the pseudo second order with k value of 14.5825 g/mg.menit and qe value of 0.1291 mg /g and R2 of 0.9967, then get the equation: (5) Conclusions From the present study, it can be concluded that the contact time is directly proportional to the efficiency and adsorption capacity. The results showed that the adsorption capacity and efficiency are higher under acidic (pH = 4) and alkaline (pH = 8) conditions. The calculation results show that the adsorption kinetics of the reaction followed a pseudo-second order. The efficiency and adsorption capacity using guava leaves reached the optimal level with a contact time of 30 minutes under the current experimental conditions.