Obama's trip to Krakow will "express the depth of our condolences to an important and trusted ally, and our support for the Polish people," a White House statement said.
Kaczynski, central bank Governor Slawomir Skrzypek and the top four generals in Poland's armed forces were among 96 people killed when their plane crashed in foggy weather near Smolensk, Russia.
The group, which included Poland's first lady, Maria Kaczynska, was flying to a ceremony to commemorate the execution of thousands of Polish military officers, policeman and other officials by Soviet secret police during World War II.
Kaczynski will be buried in a state funeral at the Wawel Castle in Krakow, the resting place of Poland's medieval kings, Cardinal Stanislaw Dziwisz, the city's archbishop, said.
A date for elections to select his successor may be set as early as , acting President Bronislaw Komorowski said.