Longitudinal viscosity of coconut water with soluble solids content (SSC) between 7 and 60 degrees Brix has been assessed using a high frequency ultrasonic method which consists in measuring the ultrasonic velocity and attenuation of longitudinal waves. These measurements have been linearly correlated with those obtained with flow tests performed with a rheometer. Thanks to their non destructive character, and to the fact that ultrasound can propagate through tubes and pipes, this ultrasonic approach and the linear relation proposed are recommended for in line measurements during coconut water processing. (C) 2013 Elsevier Ltd. All rights reserved.