The aim of the community service were to reduce losses of bengkoang farmers and traders, and also to optimize bengkoang tubers farmer groups with increased value added through cold mask products. Bengkoang tubers that not sell anymore and considered reject where less feasible to be food products used to make the cold mask. This community service was done by stages: 1) Making and testing of cold mask bengkoang by using 3 (three) maturity types of bengkoang tuber. The observations included rendement, white color, pH, organoleptic test of mask, and irritation test; and 2) Counseling and demonstration / training of making cold mask in group of partner. In the counseling delivered: i) Bengkoang tuber potency, ii) Factors to consider in determining reject bengkoang , and 3) Factors considered in making good quality products and can be stored for long periods. The results of this community service activity were: 1) Reject bengkoang (unsold remnant) has the potential and can and safe to be used as cold mask; 2). The cold mask product of reject bengkoang had same quality with cold mask using fresh bengkoang or old harvested bengkoang (5-5.5 month). Starch of reject bengkoang higher than fresh bengkoang and it's water content is lower; and 3). Members of farmer women group Berkat Yakin can understand and able to make cold mask from reject bengkoang and good to be stored for a long time.