Used coffee grounds (UCG) represent an organic waste stream with potential for energy recovery. This study investigates the briquetting of recycled UCG granulate, with emphasis on particle-size characteristics, moisture content, mechanical durability and the observed contribution of bonding mechanisms. UCG from Franck, Barcaffe and Escobar were analysed and briquetted using a Mekom MiniBrik-30. Four briquettes from each coffee brand were tested for mechanical durability after 500 rotations at 1 revolution per minute. Mean mechanical durability was 97.6 ± 0.7% for Franck, 95.4 ± 5.2% for Barcaffe and 97.7 ± 0.6% for Escobar (n = 4). The lower Barcaffe result was mainly associated with one briquette exhibiting 87.8% durability. A separate binder test using 5 wt.% cellulose binder (spruce sawdust) resulted in a mean mechanical durability of 97.2 ± 0.5% for the Barcaffe briquettes. The treated briquettes showed reduced variability, with all four samples exceeding the 95% acceptance criterion. The results indicate that mechanical compaction and interparticle bonding are sufficient to produce durable briquettes from the investigated UCG, while the available data do not permit the individual contributions of lignin, capillary, colloidal and adhesive mechanisms to be quantified. Under the investigated conditions, UCG could be densified into briquettes meeting a mechanical durability criterion of >95% in all four tests for Franck and Escobar, while with 5 wt.% cellulose binder, all four investigated Barcaffe briquettes met the 95% acceptance criterion (97.2 ± 0.5%), whereas one untreated Barcaffe briquette was below this criterion. The annual energy content was estimated theoretically at approximately 64.4 GWh from the estimated Slovenian UCG quantity and a literature lower calorific value of 21.08 MJ/kg; no energy-recovery experiment was performed in the present study.