The development of new adsorbent materials is a key factor for applying sorption-based technologies designed to clean effluents. Clay biomass complexes (BMMT) from fungal biomass grown on a raw montmorillonite (MMT) were generated in a previous work and used in a wet state. These samples were examined previously as a material to retain metals and improve separation after adsorption processes. The objective of this study was to characterize the uranium(VI) adsorption of previously dried BMMT, to determine differences from wet BMMT samples, and to understand some of the processes responsible for those differences. The differences between dried and wet BMMT adsorption capacities were verified. Proton exchange of dried BMMT samples was analyzed. Furthermore, X-ray diffraction and zeta-potential measurements of the samples after uranium(VI) uptake were performed. The hydration degree during the adsorption contact time was evaluated. Contact-angle measurement and diffusion experiments by Fourier transform infrared spectroscopy were also conducted. Dried BMMT samples presented a higher uranium(VI) uptake capacity than wet BMMT samples. Biomass played an important role in the behavior of samples evaluated, and the results indicated the importance to specify the hydration degree of adsorbents.