Abstract B-bromo-or B-iodo-9-borabicyclo [3.3. 1] nonane reacts readily with 1-alkynes. Such haloboration reactions proceed through the Markovnikov addition of the XB moiety to C C bonds and cis fashion. The bromoboration reaction occurs chemoselectively at terminal C C bonds but not at internal C C, terminal and internal C C bonds. The protonolysis of haloboration products with acetic acid gives corresponding 2-bromo-or 2- ...