Context : Young open clusters provide important clues to the interface between the main sequence and pre-main-sequence phases of stellar evolution .
The young and nearby open cluster IC 2391 is well-suited to studies of these two evolutionary phases .

Aims : We establish a bona fide set of cluster members and then analyze this set in terms of binary frequency , projected rotational velocities , [ Fe/H ] , and lithium abundance .
In the wake of the Hipparcos distance controversy for the Pleiades , we compare the main-sequence fitting distance modulus to the Hipparcos mean parallax for IC 2391 .

Methods : We have obtained new proper motions for 6991 stars down to V \sim 13-16 over a \sim 9-deg ^ { 2 } area of the sky comprising IC 2391 .
The precision of proper motions , \sigma _ { \mu } = 1.7 mas yr ^ { -1 } , allowed us to calculate reliable membership probabilities .
We also obtained precise radial velocity and v \sin i measurements with Coravel and FEROS for 76 probable cluster members .
The cluster ’ s mean radial velocity is +14.8 \pm 0.7 km s ^ { -1 } .
The FEROS high-resolution spectra were used to determine both the [ Fe/H ] abundance in the four main sequence dwarfs of IC 2391 and the Li abundance in 47 stars .
In addition , new BV CCD photometry was obtained for the majority of probable cluster members .

Results : The proper-motion survey covers a 6 times larger sky area than the prior targeted searches for cluster members in IC 2391 .
A total of 66 stars are considered bona fide cluster members down to a mass equivalent to 0.5M _ { \sun } .
A quarter of them have been newly identified with many in the F2-K5 spectral range , which is crucial for a main-sequence fit .
We find a mean [ Fe/H ] value of +0.06 \pm 0.06 , when a solar abundance of \log \epsilon ( Fe ) =7.45 is adopted .
The main sequence fitting yields a distance modulus that is 0.19 mag larger than that derived from Hipparcos parallaxes ; thus this offset nearly has the size of a similar offset found for the Pleiades .
The Li abundance pattern is similar to the earlier findings and is typical for a 40 Myr old open cluster .

Conclusions : A variety of new data on the probable members of IC 2391 improve essentially all observational parameters of this young open cluster .