Cyanide-contaminated wastewater is a very important problem of negative environmental impact. The objective of the research was the reduction of cyanide in the contaminated water emitted in a gold recovery process in the district of Chala-Arequipa after being used in mining processes, the method used was the formation of a microbial biofilm on suitable supports for its growth. The presence of cyanide in two water samples before treatment was 1,352 mg/L respectively. The treatment was performed in bioreactors with biofilms of Pseudomona aeruginosa and Escherichia coli supported on polypropylene and polyurethane for biofilm formation and growth. The tests were conducted over a period of 5, 6 and 7 days, obtaining the following results: in test 1, with Pseudomona aeruginosa biofilms, the cyanide concentration was reduced to 38.98 mg/L (97.11 %), with a pH of 10.77, total suspended solids at 10.79 mg/L, electrical conductivity at 10. 63 mg/L and turbidity at 7.46 NTU; test 2, in bioreactors with Escherichia coli biofilms was also favourable, decreasing cyanide to 325.1 mg/L (75.95 %), with a pH of 8.7, total suspended solids at 1.43 mg/L, dissolved oxygen at 6.70 mg/L, electrical conductivity at 51.13 µS/cm and turbidity at 7.13 NTU. Thus, it was established that the biofilms of Pseudomona aeruginosa and Escherichia coli constitute an environmentally sustainable methodology for the reduction of cyanide in water, which can be complemented with other technology to culminate with the elimination or removal of cyanide to levels below the maximum permissible limits of the environmental quality standards, avoiding the negative impacts that these discharges produce to ecosystems and human beings.