The potential of seaweeds as food is gaining increasing interest among Western consumers. This trend is supported by the nutritional benefits of several species such as Palmaria palmata. Product flavor is a major factor governing consumer acceptance. Developing more attractive flavors in edible seaweeds is a key to sustain the current health food movement based on this resource in Europe. Semi-dry (SD) storage of P. palmata was investigated as a means to increase its sensory quality. SD-samples containing 20% moisture and dried (D) samples (6% moisture) stored up to 126 days were studied. SD-samples stored for a long period (61 and 126 days) developed a distinct sweet, rich, complex flavor and odor as well as a softer texture compared to SD-samples stored for a shorter period (12 days) and D-samples stored for 126 days. Variations in nutritional compounds and physico-chemical properties among samples along with increasing levels and diversity of volatile compounds in SD-samples during storage compared to D-126 suggest that a variety of flavor compounds arise from biochemical reactions involving lipids, proteins and carbohydrates. These reactions are either endogenous or the result of the activity of microorganisms naturally present in the seaweed. They are promoted by a higher moisture content than in dried material (20% vs 6%) and long storage times. These results provide a basis which can be applied to control the storage conditions of seaweeds to produce flavor-rich ingredients attractive to Western consumers.