Background: Replacing the plasma in apheresis platelet concentrates (PCs) with an additive solution is desirable to avoid adverse reactions caused by plasma components. The new platelet-additive solution T-Sol (Baxter) contains acetate and citrate to balance the lactate formation from glucose. Material and Methods: 23 PCs were obtained with the Amicus double-needle collection device, divided, and suspended in either two thirds T-Sol™ or pure autologous plasma. Residual white blood cells, hemagglutinins, protein, and albumen were measured in both platelet preparations. pH values and levels of glucose, lactate and LDH were determined during a period of 5 days. Results: The content of proteins in the PCs was by two thirds lower in the T-Sol products (median 34.2 g/l, range 32.3–35.6 g/l) than in the plasma preparations (55.6 g/l, 54.7–59.8 g/l) (p < 0.05). The hemagglutinin titers were also significantly reduced in the T-Sol group (p < 0.05). The pH values remained stable in both platelet preparations during 5 days. Consumption of glucose and releases of lactate and LDH occurred in both storage conditions, but were significantly lower in the T-Sol group at all time points (p < 0.05). Furthermore, the day-to-day changes in glucose and lactate were significantly less in the T-Sol PCs (p < 0.05). Conclusions: Our data indicate that suspension of apheresis platelets in T-Sol allow blood group-incompatible transfusions without manipulation. During storage, T-Sol PCs maintain a stable pH and have less changes in biochemical markers than pure-plasma PCs.