The current investigation aimed to study the suitability of buckthorn leaves - without any further treatment as a readily available and inexpensive adsorbent for recovering cobalt cations from contaminated aqueous solutions using a batch-type adsorption unit under various operating agents. The source of buckthorn leaves used was from perennial trees in the city of Baghdad, and the fresh leaves were carefully collected before being washed, dried, ground, and prepared to be an adsorption medium. The results obtained indicated that buckthorn leaves were remarkably efficient in removing cobalt cations from contaminated aqueous media, reaching 72.45% of 45 ppm at 6, 400 rpm, 150 minutes, and 7 g for each of pH, agitation speed, contact time, temperature, and adsorbent dosage, respectively. Thus, agricultural waste has proven its ability to be an important source of useful materials instead of being disposed of as waste that requires effort and cost to remove.