The objective of this study is to find the optimal configuration of a He-cooled molten Li (HCML) blanket in terms of tritium breeding ratio (TBR). A parametric optimization study is performed to assess the impact of thickness and position of neutron reflectors. As the neutron reflector, Be, (B4C)-B-11, graphite, and TiC are considered. In spite of some unfavorable material properties, Be appears to be far superior to others from the TBR point of view. It is shown that a graphite-reflected HCML blanket can provide a sufficient TBR without a neutron multiplier if the reflector is utilized in an optimal way. For a graphite-reflected HCML blanket, the impact of the Li-6 composition on TBR is also investigated. In addition, the blanket neutron energy multiplication factor (NEM) and the distribution of nuclear heating are evaluated. (c) 2005 Elsevier B.V. All rights reserved.