Eucalyptus grandis wood was ca. 80% delignified in 79-92% (v v-1) formic acid containing 0.22% (w v-1) HCl as a catalyst under reflux and mechanical stirring for 90 min. Pulps obtained under these conditions presented pulp yield, Kappa number and Klason lignin in the ranges of 44-52%, 30-40 and 8-10%, respectively. The presence of water in the experiments with the more diluted formic acid concentration (79%) showed a beneficial effect on the pulp fiber length and pulp yield. Formic acid sawdust treatments were carried out under the best chip pulping conditions. Plots of yield versus lignin loss show comparable delignification selectivity for sawdust and chips. The most selective pulping experiments were those with 79% formic acid employing a mechanical stirrer blade of polytetrafluorethylene (PTFE) and those with 99% formic acid using a stainless steel blade.473247256