Iodine is one of the essential nutrients that needed for thyroxin hormone formation, hormone that can adjust the rate of substance exchange which affect the human's growth and development rate. Eucheuma cottonii has been proved to contain high iodine level. By combining Eucheuma cottonii and tamarinds as jam ingredients, it is expected fulfill iodine needs and will improve the product acceptance of consumer. The research started by combining three different ratios of tamarind and sugar, and five different pectin concentrations on tamarind jam's formulation. The best formulation was the jam with 25:75 ratios of tamarind and sugar, and using 0.25% of pectin concentration. The second step of research was to investigate the effect of seaweed concentration addition into jam. The result of the research indicated that the jam with highest iodine content and accepted well by consumers was jam with 15% seaweed concentration. So, it is concluded that the best formulation for tamarind jam in term of iodine content and overall acceptance is 25% tamarind, 75% sugar, 0.25% pectin, and 15% Eucheuma cottonii. From formulation above, the final jam contained 37.15% water, 0.57% ash, 0.29% protein, 1.53% fat, 60.45% carbohydrate, 59.19% total sugar, and 0.764 water activity. According to microbiology analysis performed in four weeks storage, the tamarind jam could still be consumed until week four.