  We present a magnetic-field surface map for both stellar components of the
young visual binary ksi Boo AB (A: G8V, B: K5V). Employed are high resolution
Stokes-V spectra obtained with the Potsdam Echelle Polarimetric and
Spectroscopic Instrument (PEPSI) at the Large Binocular Telescope (LBT). Stokes
V line profiles are inverted with our iMAP software and compared to previous
inversions. We employed an iterative regularization scheme without the need of
a penalty function and incorporated a three-component description of the
surface magnetic-field vector. The spectral resolution of our data is 130,000
(0.040-0.055A) and have signal-to-noise ratios (S/N) of up to three thousand
per pixel depending on wavelength. A singular-value decomposition (SVD) of a
total of 1811 spectral lines is employed for averaging Stokes-V profiles. Our
mapping is accompanied by a residual bootstrap error analysis. Magnetic flux
densities of the radial field component of up to plus/minus 115 +/- 5 G were
reconstructed for ksi Boo A while up to plus/minus 55 +/- 3G were reconstructed
for ksi Boo B. ksi Boo A's magnetic morphology is characterized by a very high
latitude, nearly polar, spot of negative polarity and three low-to-mid latitude
spots of positive polarity while ksi Boo B's morphology is characterized by
four low-to-mid latitude spots of mixed polarity. No polar magnetic field is
reconstructed for the cooler ksi Boo B star. Both our maps are dominated by the
radial field component, containing 86 and 89 percent of the magnetic energy of
ksi Boo A and B, respectively. We found only weak azimuthal and meridional
field densities on both stars (plus/minus 15-30 G), about a factor two weaker
than what was seen previously for ksi Boo A. The phase averaged longitudinal
field component and dispersion is +4.5 +/- 1.5G for ksi Boo A and -5.0 +/- 3.0
G for ksi Boo B.
