Whey is a byproduct of cheese making. Disposal of whey may cause environmental pollutions. Whey protein isolate (WPI) is obtained from whey via ion-exchange and ultra-filtration, and contains more than 90% of protein. Most current commercially available paper glue products are made from undegradable synthetic polymers and may be harmful to human. The objective of this study was to develop environmentally friendly and children safe paper glue using WPI and sucrose as major ingredients. Results showed that both desirable bonding strength and viscosity of the safe paper glue were achieved by adding sucrose. The whey protein and sucrose based paper glue had excellent recovered bonding strength (ideal for self-seal envelopes) and bonding strength to different substrates (paper–paper, paper–wood, paper–plastic, and paper–metal). Shelf life tests indicated that the safe glue was stable with addition of low level of preservative and there were no considerable changes in bonding strength and viscosity during the storage at 23°C or 40°C for up to 1 year. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 39710.