With the White House rivals in a dead heat six weeks before election day, Clinton from the get-go painted her Republican rival as out of touch and having a tenuous relationship with the truth, willing to say "crazy things" to get elected.
"You live in your own reality" said the 68-year old Democrat, who accused Trump of launching his political career on a "racist lie" -- the birther conspiracy theory that questioned President Barack Obama's citizenship.
Trump, who faces tough questions about his suitability for the Oval Office, started out with a more restrained tone -- he even ditched his red power tie for a more statesmanlike blue.
But he quickly went on the offensive, repeatedly interrupting Clinton with verbal jabs.
The celebrity businessman branded Clinton a "typical politician. All talk, no action. Sounds good, doesn't work."
'Trumped up, trickle-down'
In feisty exchanges on the economy, Trump reprised the themes that have catalyzed his improbable campaign, blaming Clinton and the political class for losing jobs to Mexico and China through bad trade deals.
"Our country is suffering because people like secretary Clinton have made such bad decisions in terms of our jobs and in terms of what's going on," he said.
He demanded Clinton -- a former secretary of state, first lady and US senator -- account for her time in government: "You've been doing this for 30 years. Why are you just thinking about these solutions right now? For 30 years, you've been doing it."
Clinton responded by accusing Trump of having "stiffed" small businesses throughout his business career.
Demanding Trump release his taxes, in keeping with election custom, she accused him of backing an economic platform amounting to "the most extreme" package of tax cuts for the wealthy in US history.
"I call it trumped up trickle-down, because that's exactly what it would be," she quipped.
Trump said he would release his tax returns, "when she releases her 33,000 e-mails that have been deleted," alluding to the Democrat's use of a private email server as secretary of state.
