The Kenyan government has said it will buy up all the country's available maize stocks to feed those in the drought-stricken north-east.
Aid agencies say water sources are drying up
Describing the situation as "very severe", it said it would put aside $14m (£7.9m) to purchase the maize.
Kenya says its main priority is to feed the 2.5 million people at immediate risk, almost 10% of the population.
The United Nations food agency has warned that 11 million people across the Horn of Africa need food aid.
The Kenyan government has said conditions in the north-eastern provinces are a national disaster, with 2.5 million people expected to need aid to survive beyond the end of February.
According to the UN's Food and Agriculture Organization (FAO), the Kenyan districts of Marsbait, Mandera and those far south such as Kajiado, Laikipia and parts of Eastern Province are the worst-affected.
Aid agencies working in the area have issued an appeal for funds, warning that water sources are drying up and animals dying.
Kenya: 2.5m people
A BBC correspondent in northern Kenya says the corpses of cattle and donkeys are lying everywhere.
The BBC's Adam Mynott says six children have died in the past three weeks in Wajir hospital from hunger-related diseases and 15 of the hospital's 20 beds are occupied by malnourished children in varying states of health.
While trees with deep roots are still managing to push up a few scant leaves, everything else is brittle, brown and dry as tinder, he says.
As well as Kenya, the FAO has warned that Ethiopia, Djibouti and Somalia are badly affected by severe drought - with Somalia particularly at risk.