The adsorptions of acetic, propionic, butyric, and valeric acids from aqueous solutions on a series of coconut charcoals of different degrees of activation were determined. For purposes of interpretation the numbers of millimoles adsorbed per gram of charcoal were compared for pairs of acids. Unimolecular adsorption of the acids is indicated. Surface areas of the charcoal series were estimated. They range from 130 to 625 sq. m. per gm. of charcoal, depending on the adsorbate used and the degree of activation of the charcoal. Some insight into the activation process is given.