At 0836 GMT, commercial banks quoted the shilling at100.50/70 to the dollar, compared with Wednesday's close of100.35/45.
"It's demand and supply. Supply is mostly from NGOs; demand is the usual culprits - energy, telecom and manufacturers," said a senior trader at one commercial bank said.
The trader said the shilling touched 100.80/90 earlier in the session, a 3 1/2-year low last seen in October 2011, before re gaining some ground.
The shilling has been under sustained pressure heading towards a record low around 107, caused by dwindling tourism revenues, a widening current account deficit and a stronger dollar on global markets.
Technical analysis of the 14-day and 50-day weighted moving averages suggested the shilling would stay on a weakening trend in the near term.
--reuters--