Handwashing with soap reduces the transmission of diarrheal pathogens, but access to hand-washing facilities, water, and soap in humanitarian emergencies is limited. The SuperTowel® (ST) is a fabric treated with permanent antimicrobial bonding and has been designed as a soap alternative in emergency situations. The aim of this study was to test the efficacy of the ST as a hand-cleaning product. Two sets of laboratory tests, with 16 volunteers in each, were conducted to test the efficacy of different prototypes of the ST. Volunteers pre-contaminated their hands with nonpathogenic Escherichia coli. Comparisons were made between hand cleaning with the ST and handwashing with the reference soap, using a crossover design. Participants also completed a questionnaire about product perceptions. Three of the prototypes of the ST were more efficacious at removing E. coli from pre-contaminated hands than handwashing with soap (mean log10 reduction of 4.11 ± 0.47 for ST1, 3.84 ± 0.61 for ST2, and 3.71 ± 0.67 for ST3 versus 3.01 ± 0.63 for soap [P < 0.001, P = 0.002, and P = 0.005, respectively]). The ST prototypes used less water than handwashing with soap, were well accepted, and were considered preferable in communal settings. The ST has the potential to be a suitable complementary hand-cleaning product for humanitarian emergencies.