The yield on the 182-day bill dropped to 11.267 percent from 11.925 percent last week.
The bank received bids worth 22.8 billion shillings ($225 million) for the 12 billion shillings it offered across the two bonds. It accepted 15 billion shillings.
Next week, the bank will sell bills of all maturities worth a total 16 billion shillings in two separate auctions, it said.