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We present the first limits on the Epoch of Reionization (EoR) 21-cm HI powerspectra, in the redshift range $z=7.9-10.6$, using the Low-Frequency Array(LOFAR) High-Band Antenna (HBA). In total 13\,h of data were used fromobservations centred on the North Celestial Pole (NCP). After subtraction ofthe sky model and the noise bias, we detect a non-zero $\Delta^2_{\rm I} = (56\pm 13 {\rm mK})^2$ (1-$\sigma$) excess variance and a best 2-$\sigma$ upperlimit of $\Delta^2_{\rm 21} < (79.6 {\rm mK})^2$ at $k=0.053$$h$cMpc$^{-1}$ inthe range $z=$9.6-10.6. The excess variance decreases when optimizing thesmoothness of the direction- and frequency-dependent gain calibration, and withincreasing the completeness of the sky model. It is likely caused by (i)residual side-lobe noise on calibration baselines, (ii) leverage due tonon-linear effects, (iii) noise and ionosphere-induced gain errors, or acombination thereof. Further analyses of the excess variance will be discussedin forthcoming publications.

Upper limits on the 21-cm Epoch of Reionization power spectrum from one night with LOFAR