This work presents the results of measurements of the effective thermal conductivity of Li2O and Be pebble beds using a hot wire method1. Also, preliminary results for a binary bed using Al2O3 pebbles are presented. The measured value for an Al2O3 single packing bed showed good agreement with Schulunder's correlation2 and Hall-Martin's correlation3 with a contact area fraction of 5 × 10−5. The value of the contact area fraction in this study showed consistency with that reported by Dalle Donne et al.4. Results for the binary bed of Al2O3 (0.3 mm and 3 mm) pebbles showed good agreement with the same correlation using the same value of contact area fraction. The measured value of the effective thermal conductivity for an Li2O bed using 1 mm pebbles agreed with the correlation using a value of 4.9 × 10−3 for the contact area fraction. The measured values of the effective thermal conductivity for 0.6 mm and 1mm Be pebble beds showed consistency with the correlation using 1 × 10−4 for the contact area fraction.