Beet and cane molasses are produced worldwide and widely used in ruminant rations to improve diet palatability and sugar content. However, DM composition is not fully described, and even variability is not considered. Objective of this study was to analyze different molasses to better characterize their composition. Sixteen cane (CM) and 16 beet molasses (BM) were sourced worldwide and analyzed. Gravimetric method was used to determine DM, Kjeldahl for CP, sugars and starch via enzymatic method, minerals by ICP, organic acids and other components in HPLC. Statistical analysis was conducted via ANOVA using the JMP-12 software. Significance was declared for P < 0.05. This approach was able to characterize 97.4% and 98.3% DM of CM and BM, respectively. CM showed a numerically lower dry matter content as fed (a.f.) compared with BM (76.8 ± 1.02 vs 78.3 ± 1.61%), as well as CP content (4.8 ± 1.7 vs 10.5 ± 1.1% a.f. P < 0.05), with a minimum value of 1% in CM to a maximum of 12% a.f. in BM. The amount of sucrose was higher in BM compared with CM (48.4 ± 1.5 vs 37.5 ± 4.8% a.f. P < 0.05), but with great variability even within CM (51.00 max to 33.31 min, % a.f.) and BM (52.00 max to 33.31 min, % a.f.). Glucose and fructose were detected in CM (4.06 ± 2.07 and 6.20 ± 2.17% a.f., respectively), showing high variability. Organic acid composition differed among molasses. Lactic acid was more concentrated in CM compared with BM (4.69 ± 2.16 vs 3.48 ± 1.37% a.f.), varying from 9.77% maximum to 1.23% minimum within CM, and from 5.55% maximum to 1.37% minimum in BM. Aconitic acid was found only in CM, while glycolic acid in BM. The total sum of acids ranged from 2% to 14% a.f. Sulfates, phosphates, and chlorides had a higher concentration in CM, which showed a lower DCAD compared with BM (4.47 ± 4.97 vs 53.94 ± 33.36 mEq/100g a.f. P < 0.05). Within the cane group, it varied from +117.63 to −58.59 mEq/100g a.f., while in beet from +129.20 to +3.24 mEq/100g a.f. In conclusion, data obtained in this study demonstrates the significant differences in molasses composition, highlighting that a more accurate description and characterization is possible and strictly required especially if its use in animal feed is to be fully optimized.