Abstract—Copper is a heavy metal that has been used as an anti-fungal agent in various crops, this is why it accumulates in certain agricultural lands at levels that become toxic to plants, as well as to microflora. Cooper, although essential to plants, is toxic when found in high concentrations. The objective of this study was to determine if this element is capable of stimulating and at the same time inhibiting germination of seeds of Prosopislaevigata (mesquite) depending on concentration of CuS04.5H20 solutions. A completely randomized experimental design with seven treatments and three repetitions was used to determine tolerance of mesquite seeds to copper. The variables evaluated were percentage of daily germination (PDG-A, PDG-B, and PDG-C), accumulative germination (AG-A, AG-B, and AG-C), average germination time (AGT), germination rate (GR) and anhydrous weight (AW) of mesquite seeds. The culture media supplied with concentration of 10-4 M of copper sulfate (CuS04.5H20), corresponding to treatment four (T4) showed significant differences (p≤0.05) in variable percentage of daily germination at 48 hours (PDG-B), which presented a germination of 66.7% in relation to treatment two (T2) with a concentration of 10-2 M of CuS04.5H20 and germination of 22.2%. Results obtained after 72 hours for percentage daily germination variable (PDG-C) with>p<0.1 showed that mesquite is a species that can tolerate and adapt in germination stage for culture medium with concentrations from 10-2 to 10-7M of CuS04.5H20, and consequently use of seedlings for phytoremediation of sites contaminated with copper.