Starch nanocrystals (SNCs) are insoluble particles isolated from starch granules' crystalline structure. SNCs production is mainly based on acid hydrolysis of different starches with low yield and broad properties and uses. Some starch modifications or pretreatments can improve the SNC production and narrow its properties. This study focuses on investigating the effect of pretreatments (heat-moisture-treatment [HMT], annealing [ANN], and sonication [SNT]) associated with H2SO4 [3M] to produce Carioca Bean SNC after 5 and 7 days of acid hydrolysis. The yield and hydrolysis kinetics were studied. The molecular structure was examined by gel permeation chromatography (GPC), crystallinity by FTIR-ATR and x-ray diffractometry and, thermal stability by differential scanning calorimetry (DSC). All starches hydrolysis is described by a first-order model reaction and shown two phases related at k values, and SNT speeds up the reaction. The acid hydrolysis is characterized by a rapid (0–3 days) stage, followed by a slow phase lasing 3–7 days. Carioca bean SNC yield was at least 180% higher than the reports with the same methodology. The HMT increases the yield of the SNCs as compared with the native starch (yield 35.2% - 42.3%). The starch A-type crystallites seem to be more resistant to acid hydrolysis than B-type ones due to the vanishing of the B-type revealed as an X-ray characteristic peak at 5.7°. Also, the short-range molecular order was lost, and the ratio of 1047/1022 cm-1 and 1022/995 cm−1 was reduced with acid hydrolysis. The ANN improves crystallites' perfection, protecting them from acid attacks, improving thermal stability. The pretreatments allow carioca bean starch to be a promising feedstock to produce SNCs with good yield and RC. In addition, ANN can improve the thermal stability and SNT to speed up the hydrolysis for SNCs production, while HMT can increase the hydrolysis yield.