The solubility and diffusion of carbon dioxide into salmon, cod, anglerfish, wolf-fish and tuna fillets was determined by monitoring pressure changes over time in a closed chamber at constant temperatures. High correlation (r(2) > 0.95) between the measured solubility against the theoretical solubility of water corrected for the total water and fat content of the fish was found. The average Henry's constant for raw fish fillets at 0 degreesC was calculated to be 45.1 Pa ppm(-1) (mg CO2 per kg fish). Using the un-steady state solution of Fick's law for the pressure history from 0 to 15 h gave better measurements of the CO2 solubility in fishes than using the pressure drop over 20 h, mainly because the system does not reach equilibrium until about three days. In addition this graphical solution made determination of the diffusion coefficient possible. The average effective diffusion coefficient for CO2 into raw fish fillets at chilled and superchilled temperatures was determined to be 1.69 x 10(-5) cm(2)/s. (C) 2003 Elsevier Ltd. All rights reserved.